Compact radio frequency heating of packaged articles

ABSTRACT

Heating systems utilizing radio frequency (RF) energy and methods for using the same to rapidly and uniformly heat packaged articles moving through the system on one or more convey lines. These systems may be useful for a variety of processes, including the pasteurization or sterilization of packaged foodstuffs.

RELATED APPLICATIONS

The present U.S. utility patent application claims priority to U.S.Provisional Patent Application Ser. No. 62/574,603, filed Oct. 19, 2017,entitled “COMPACT RADIO FREQUENCY HEATING OF PACKAGED ARTICLES,” U.S.Provisional Patent Application Ser. No. 62/574,607, filed Oct. 19, 2017,entitled “HIGH INTENSITY RADIO FREQUENCY HEATING OF PACKAGED ARTICLES,”U.S. Provisional Patent Application Ser. No. 62/574,616, filed Oct. 19,2017, entitled “APPLICATION OF RADIO FREQUENCY ENERGY TO PACKAGEDARTICLES,” U.S. Provisional Patent Application Ser. No. 62/574,620,filed Oct. 19, 2017, entitled “CONVEYANCE OF PACKAGED ARTICLES HEATEDWITH RADIO FREQUENCY ENERGY,” U.S. Provisional Patent Application Ser.No. 62/574,622, filed Oct. 19, 2017, entitled “ENERGY ABSORPTIVECOMPONENTS FOR RADIO FREQUENCY HEATING OF PACKAGED ARTICLES,” U.S.Provisional Patent Application Ser. No. 62/574,630, filed Oct. 19, 2017,entitled “CONTACT MEMBERS FOR PACKAGED ARTICLES HEATED WITH RADIOFREQUENCY ENERGY,” U.S. Provisional Patent Application Ser. No.62/574,638, filed Oct. 19, 2017, entitled “RADIO FREQUENCY HEATINGAPPARATUS WITH HELICAL TRAVEL PATH FOR PACKAGED ARTICLES,” and U.S.Provisional Patent Application Ser. No. 62/574,640, filed Oct. 19, 2017,entitled “RADIO FREQUENCY HEATING PROCESS WITH RESIDENCE TIME CONTROL OFPACKAGED ARTICLES.” The entirety of the above-identified provisionalpatent applications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to systems that use radiofrequency (300 kHz to 300 MHz) energy to heat articles.

BACKGROUND

Electromagnetic radiation is a known mechanism for delivering energy toan object. The ability of electromagnetic energy to penetrate and heatan object in a rapid and effective manner has proven advantageous for anumber of chemical and industrial processes. In the past, radiofrequency (RF) energy has been used to heat articles by, for example,induction heating or dielectric heating. However, the use of RF energyto heat articles can have drawbacks. For example, the wavelength of RFenergy can make it difficult to transmit and launch RF energy in anefficient manner. The present invention involves discoveries forminimizing and/or eliminating many of the drawbacks conventionallyassociated with the use of RF energy to heat articles.

SUMMARY

One aspect of the present invention concerns a process for sterilizingor pasteurizing articles using radio frequency (RF) energy. The processcomprises the steps of: (a) passing a plurality of articles through aliquid contact zone of an RF heating system on at least one convey linewhile maintaining the articles in contact with a liquid for at least aportion of the passing, where the liquid contact zone includes aninitial thermal regulation zone, an RF heating zone, and subsequentthermal regulation zone; (b) regulating the temperature of the articleson the convey line in the initial thermal regulation zone to promotetemperature uniformity of the articles; and (c) subsequent to theregulating step, heating the articles on the convey line with RF energyin the RF heating zone to thereby increase the average temperature atthe geometric center of the articles by at least 20° C.; and (d)subsequent to the heating step, regulating the temperature of thearticles on the convey line to thereby decrease the average temperatureat the geometric center of the articles by at least 10° C. The averageresidence time of the articles in the RF heating zone is not more than10 percent of the average residence time of the articles in the liquidcontact zone.

Another embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using RF energy. The processincludes the steps of: (a) passing a plurality of articles through aliquid contact zone of an RF heating system on at least one convey linewhile maintaining the articles in contact with a liquid during at leasta portion of said passing, where the liquid contact zone includes aninitial thermal regulation zone, an RF heating zone, and a subsequentthermal regulation zone; (b) regulating the temperature of the articleson the convey line in the initial thermal regulation zone to promotetemperature uniformity of the articles; (c) subsequent to theregulating, heating the articles on the convey line with RF energy inthe RF heating zone to thereby increase the average temperature at thegeometric center of the articles by at least 20° C.; and (d) subsequentto the heating, regulating the temperature of the articles on the conveyline to thereby decrease the average temperature at the geometric centerof the articles by at least 10° C. The articles travel through theliquid contact zone on a nonlinear travel path having a total lengththat is at least 10 times greater than the linear distance between thelocations where the articles enter and exit the liquid contact zone.

Yet another embodiment of the present invention concerns a system forsterilizing or pasteurizing articles using radio frequency energy. Thesystem comprises an initial thermal regulation zone for promotingtemperature uniformity of the articles, an RF heating zone for heatingthe articles with RF energy, and a subsequent thermal regulation zonefor cooling the articles. The system also includes at least one conveyline for transporting the articles along a non-linear article travelpath through the initial thermal regulation, RF heating, and subsequentthermal regulation zones. The initial thermal regulation zone comprisesan inlet for receiving the articles and the final thermal regulationzone comprises an outlet for discharging the articles. The convey lineis configured such that the total length of the article travel path fromthe inlet to the outlet is at least 10 times greater than the lineardistance between the inlet and the outlet.

Still another embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using radio frequency energy. Theprocess includes the steps of: (a) discharging RF energy into an RFheating zone; (b) passing a plurality of said articles through the RFheating zone on at least one convey line; (c) heating the articles onthe convey line with at least a portion of the RF energy discharged intothe RF heating zone, where the heating is sufficient to increase theaverage temperature at the geometric center of the articles by at least20° C. to a temperature of at least 65° C. During the heating, thearticles absorb RF energy at an average lengthwise energy absorptionrate of at least 2×10⁵ Joules per foot.

A further embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using radio frequency energy. Theprocess includes the steps of: (a) discharging RF energy into an RFheating zone; (b) passing a plurality of said articles through the RFheating zone on at least one convey line; and (c) heating the articleson the convey line with at least a portion of the RF energy dischargedinto the RF heating zone to increase the average temperature at thegeometric center of the articles by at least 20° C. to a temperature ofat least 80° C. During the heating, the average lengthwise heating rateat the geometric center of the articles in the RF heating zone is atleast 2° C. per foot.

A still further embodiment of the present invention concerns a systemfor sterilizing or pasteurizing articles using radio frequency energy.The system includes an initial thermal regulation zone for promotingtemperature uniformity of the articles and one or more RF energygenerators capable of generating at least 25 kW of RF power. The systemalso includes an RF heating zone for heating the articles with RF energygenerated by the RF energy generators and a subsequent thermalregulation zone for cooling the articles. The system further includes atleast one convey line for transporting the articles along an articletravel path through the initial thermal regulation, RF heating, andsubsequent thermal regulation zones. The system is configured to providethe RF heating zone with an average volumetric RF power intensity of atleast 1.5 kilowatts per cubic foot.

Another embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using radio frequency (RF) energy.The process includes the steps of: (a) passing a plurality of saidarticles through a pressure vessel on at least one convey line whilesaid articles are submerged in a liquid medium; (b) discharging RFenergy into an RF heating zone defined within at least one applicatorthat is received in the pressure vessel and is in open communicationwith the interior of the pressure vessel; and (c) heating the articleswith RF energy in the RF heating zone as the articles are passed throughthe RF heating zone on the convey line and are submerged in the liquidmedium.

Yet another embodiment of the present invention concerns a system forheating a plurality of articles using radio frequency energy. The systemincludes a pressure vessel, a convey line for transporting the articlesthrough the pressure vessel, and at least one RF applicator received inthe pressure vessel and defining an RF heating zone therein. The RFapplicator includes at least one opening that is in communication withthe interior of the pressure vessel. The system also includes an RFgenerator for producing RF energy and an RF energy transmission systemconfigured to transmit RF energy from the RF generator to the RFapplicator. At least a portion of the RF energy transmission systempenetrates at least one wall of the pressure vessel to provide RF energyto the applicator in the pressure vessel.

Still another embodiment of the present invention concerns a system forheating a plurality of articles using radio frequency (RF) energy. Thesystem comprises a split applicator configured to provide a resonantcavity for RF energy. The split applicator comprises an upper sectionand a lower section and at least one opening defined between the upperand lower sections. The system further comprises at least one RFwaveguide configured to propagate RF energy toward the split applicatorand an RF conveyor configured to transport a plurality of the articlesthrough the split applicator. The RF conveyor comprises a plurality ofconvey arms extending through the opening in the split applicator andconfigured to engage and transport the articles through the splitapplicator.

Yet another embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using radio frequency energy. Theprocess comprises the steps of: (a) loading a plurality of said articlesonto an RF zone conveyor in a loading zone; (b) transporting thearticles through an RF heating zone using the RF zone conveyor whileheating the articles with RF energy in the RF heating zone; and (c)unloading the articles from the RF zone conveyor in an unloading zone.The RF zone conveyor comprises a plurality of spaced apartarticle-supporting members coupled to a drive mechanism that moves thearticle-supporting members through the RF heating zone. The loading stepincludes loading each of the articles in an article-receiving spacedefined between adjacent ones of the article-supporting members and theunloading step includes unloading each of the articles from thearticle-receiving space. The size of the article-receiving space islarger in the loading and unloading zones than in the RF heating zone.

A further embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using radio frequency energy. Theprocess includes the steps of: (a) loading a plurality of articles ontoan RF zone conveyor in a loading zone, where the RF zone conveyorcomprises a plurality of spaced-apart convey arms, each elongated alonga longitudinal axis, and where the loading includes placing each of thearticles between and in contact with a pair of the convey arms; (b)transporting the articles through an RF heating zone along a heatingpath using the RF zone conveyor while heating the articles with RFenergy in the RF heating zone; (c) unloading the articles from the RFzone conveyor in an unloading zone; and (d) returning the convey arms tothe loading zone along a return path. The convey arms travel along atleast a portion of the heating path in a heating orientation and travelalong at least a portion of the return path in a return orientation. Thedirection of extension of the longitudinal axis of the convey arms inthe return orientation is skewed at least 45 degrees from the directionof extension of the longitudinal axis of the convey arms in the heatingorientation.

A still further embodiment of the present invention concerns a radiofrequency heating system for heating a plurality of articles. The systemcomprises an RF heating zone for heating a plurality of the articleswith RF energy and a swing arm conveyor for transporting the articlesthrough the RF heating zone. The swing arm conveyor comprises aplurality of spaced apart elongated convey arms each defining a freeend, a connected end, and a longitudinal axis extending from theconnected end to the free end. The system comprises a continuous drivemechanism coupled to the connected ends of the convey arms and thecontinuous drive mechanism moves the convey arms along a convey armtravel path that includes a heating path and a return path. The systemcomprises a support system for supporting the convey arms along at leasta portion of the convey arm travel path. The support system supports theconvey arms in a heating orientation along at least a portion of theheating path and in a return orientation along at least a portion of thereturn path. The direction of extension of the longitudinal axis of eachof the convey arms in the return orientation is skewed at least 45degrees from the direction of extension of the longitudinal axis of eachof the convey arms in the heating orientation.

Still another embodiment of the present invention concerns a system forsterilizing or pasteurizing articles using radio frequency energy. Thesystem comprises an RF generator for generating RF energy, an RF heatingzone for heating the articles using RF energy generated by the RFgenerator, and an RF zone conveyor for transporting the articles throughthe RF heating zone. The RF zone conveyor comprises a plurality ofarticle contact members each comprising an energy-absorptive component,and the article contact members are configured to contact the packagesof the articles. The energy-absorptive component has a dielectricconstant in the range of 20 to 150 and a dielectric loss factor in therange of 10 to 1500.

A further embodiment of the present invention concerns an apparatus foruse in a pasteurization or sterilization system. The apparatus includesan ingestible substance, a sealed package surrounding the ingestiblesubstance, and at least one article contact member contacting and atleast partially supporting the sealed package. The article contactmember includes an energy-absorptive component and the energy-absorptivecomponent has a dielectric constant within 50 percent of the averagedielectric constant of the ingestible substance. The energy-absorptivecomponent has a dielectric loss factor within 50 percent of the averagedielectric loss factor of the ingestible substance and theenergy-absorptive component comprises a composite material that includesat least one of (i) a polymeric binder and a plurality of solidparticles dispersed in the polymeric binder and (ii) a solid electrolytematerial.

A still further embodiment of the present invention concerns anapparatus for use in a system for pasteurizing or sterilizing articlesusing radio frequency energy. The apparatus comprises an articlesupporting member configured to support the articles duringpasteurization or sterilization and an energy-absorptive contact membercoupled to the article supporting member and configured to contact atleast a portion of the package of the articles. The article contactmember comprises an energy-absorptive component and theenergy-absorptive component includes a composite material comprising atleast one of (i) a polymeric binder and a plurality of solid particlesdispersed in the polymeric binder and (ii) a solid electrolyte material.The article supporting member is formed of a dielectric material havinga dielectric loss factor of less than 10 or a conductive material havinga conductivity of at least 1×10⁶ Siemens per meter and the compositematerial has a dielectric constant in the range of 40 to 60 and adielectric loss factor in the range of 200 to 800.

Yet another embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using radio frequency energy. Theprocess comprises the steps of: (a) transporting a plurality of articlesthrough an RF heating zone using an RF zone conveyor; (b) simultaneouslywith the transporting, heating the articles with RF energy in the RFheating zone. The RF zone conveyor comprises a plurality of articlecontact members at least partially surrounding and supporting thearticles in the RF heating zone. Each of the article contact memberscomprises an energy-absorptive component having a dielectric constant inthe range of 20 to 150 and a dielectric loss factor in the range of 10to 1500.

Still another embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using radio frequency energy. Theprocess includes the steps of: (a) loading a plurality of the articlesonto an RF zone conveyor in a loading zone, where the loading includesinitiating contact between the packages of the articles and contactsurfaces of article contact members of the RF zone conveyor, and thecontact surfaces have an initial contact surface temperature immediatelybefore contacting the packages of the articles in the loading zone; (b)transporting the articles through an RF heating zone via the RF zoneconveyor while supporting the articles with the article contact membersand maintaining the packages of the articles in contact with the contactsurfaces, where each of the article contact members comprises anenergy-absorptive component having a dielectric constant in the range of20 to 150 and a dielectric loss factor in the range of 10 to 1500; (c)simultaneously with the transporting, heating the articles and thecontacting members using RF energy discharged into the RF heating zone,where the heating causes the temperature of the geometric center of thearticles to increase by at least 20° C.; (d) unloading the articles fromthe RF convey line in an unloading zone, where the unloading includesremoving the packages of the articles from contact with the contactsurfaces of the article contact members, the contact surfaces have afinal contact surface temperature immediately after removing thepackages of the articles from contact with the contact surfaces in theunloading zone, and the final contact surface temperature is at least20° C. greater than the initial contact surface temperature; and (e)returning the article contact members from the unloading zone to theloading zone. During the returning, the temperature of the contactsurfaces of the article contact members is reduced to a temperaturewithin about 5° C. of the initial contact surface temperature.

A still further embodiment of the present invention concerns a processfor sterilizing or pasteurizing articles using radio frequency. Theprocess includes the steps of: (a) providing at least one article to betreated in the RF heating system, where the article comprises aningestible substance in a sealed package; (b) determining at least oneof an average dielectric constant and an average dielectric loss factorfor the ingestible substance; (c) making an article contact member forthe article, where the making includes forming an energy-absorptivecomponent of the article contact member, the energy-absorptive componenthas a dielectric constant within 50 percent of the average dielectricconstant of the ingestible substance and a dielectric loss factor within50 percent of the average dielectric loss factor of the ingestiblesubstance; (d) at least partially surrounding the packaged article withthe contact member; and (e) while the article is at least partiallysurrounded by the contact member, heating the ingestible substance andthe energy-absorptive component with RF energy in an RF heating zone.The heating increases the temperature of the coldest portion of theingestible substance by at least 20° C.

Yet another embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using radio frequency energy. Theprocess includes the steps of: (a) heating a plurality of first articlesin an RF heating zone while transporting the first articles through theRF heating zone on a convey line having a first configuration, where theconvey line having the first configuration comprises a continuous drivemember and a plurality of spaced-apart article supporting members forsupporting the first articles; (b) replacing at least a portion of theplurality of first article supporting members with a plurality of secondarticle supporting members to thereby provide a convey line having asecond configuration; and (c) heating a plurality of second articles inthe RF heating zone while transporting the second articles through theRF heating zone via the convey line having the second configuration. Thefirst and second articles have different dimensional and/or dielectriccharacteristics and the first and second article supporting members aredifferently configured to account for the different characteristics ofthe first and second articles.

Still another embodiment of the present invention concerns an apparatusfor thermally treating a plurality of articles. The apparatus includes avessel comprising an article inlet for receiving the articles into thevessel and an article outlet for discharging the articles from thevessel and a conveyor received in the vessel and operable to transportthe articles away from the article inlet toward the article outlet. Theconveyor comprises a track configured to guide the articles on a conveypathway that includes a first substantially helical path having aplurality of vertically-spaced tiers and a plurality of spaced-apartpusher members configured to push the articles along the firstsubstantially helical path.

A still further embodiment of the present invention concerns a systemfor pasteurizing or sterilizing articles using radio frequency (RF)energy. The system includes an initial thermal regulation zonecomprising an initial helical conveyor, an RF heating zone comprising alinear conveyor, and a subsequent thermal regulation zone comprising asubsequent helical conveyor.

Yet another embodiment of the present invention concerns a process forsterilizing or pasteurizing articles using radio frequency RF energy.The process includes the steps of: (a) passing a plurality of articlesthrough an initial thermal regulation zone; (b) heating the articles anRF heating zone, where at least a portion of the heating is performedusing RF energy; and (c) passing the articles through a subsequentthermal regulation zone. The passing through the initial thermalregulation zone and/or the subsequent thermal regulation zone includespushing the articles relative to a track that guides movement of thearticles along a substantially helical path having a plurality ofvertically-spaced tiers.

Still another embodiment of the present invention concerns a process fortreating a plurality of articles. The process includes the steps of: (a)transporting a plurality of articles through a first zone using aninitial continuous conveyor; (b) transitioning the articles from theinitial continuous conveyor to an indexing conveyor, which includesintermittently loading individual articles into discretearticle-receiving spaces defined along a convey path of the indexingconveyor; (c) transporting the articles through a second zone using theindexing conveyor, which includes incrementally moving the articles inan intermittent manner along the convey path of the indexing conveyor;(d) transitioning the articles from the indexing conveyor to asubsequent continuous conveyor, where the transitioning includesintermittently unloading the articles out of the article-receivingspaces of the indexing conveyor; (e) transporting the articles through athird zone using the subsequent continuous conveyor; and (f) adjustingthe average residence time of the articles in the second zone relativethe average residence time of the articles in the first and/or thirdzones by changing the average number of articles on the convey path ofthe indexing conveyor.

A still further embodiment of the present invention concerns a processfor treating a plurality of articles. The process comprises the stepsof: (a) entering processing rate and residence time information into aprocess control system of a multi-zone processing apparatus; (b) usingthe process control system to calculate one or more operating parametersof the processing apparatus based on the entered processing rate andresidence time information; and (c) operating the processing apparatusaccording to the operating parameters. The step of operating includes:(i) transporting a plurality of articles through a first zone of theprocessing apparatus using an initial continuous conveyor; (ii)transitioning the articles from the initial continuous conveyor to anindexing conveyor, where the transitioning includes intermittentlyloading individual articles into discrete article-receiving spacesdefined along a convey path of the indexing conveyor, where theoperating parameters includes a loading parameter that determines howmany article-receiving spaces of the indexing conveyor are skippedduring the loading; (iii) transporting the articles through a secondzone of the processing apparatus using the indexing conveyor, where thetransporting includes incrementally moving the articles in anintermittent manner along the convey path of the indexing conveyor; (iv)transitioning the articles from the indexing conveyor to a subsequentcontinuous conveyor, where the transitioning includes intermittentlyunloading the articles out of the article-receiving spaces of theindexing conveyor; and (v) transporting the articles through a thirdzone of the processing apparatus using the subsequent continuousconveyor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the typical zones or steps of an RF heatingsystem or process configured according to various embodiments of thepresent invention;

FIG. 2 is a block diagram of the typical steps or zones of an RF heatingsystem according to various embodiments of the present invention,particularly where the system is used to pasteurize articles;

FIG. 3 is a block diagram of typical steps or zones of an RF heatingsystem according to various embodiments of the present invention,particularly where the system is used to sterilize articles;

FIG. 4 is a schematic diagram of a liquid contact zone according tovarious embodiments of the present invention, particularly illustratingone example of a non-linear article travel path through the liquidcontact zone;

FIG. 5 is a schematic diagram of a liquid contact zone according tovarious embodiments of the present invention, particularly illustratinganother example of a non-linear article travel path through the liquidcontact zone;

FIG. 6 a schematic diagram of a liquid contact zone according to variousembodiments of the present invention, particularly illustrating yetanother example of a non-linear article travel path through the liquidcontact zone;

FIG. 7 is a partial perspective view of a helical conveyor suitable foruse in one or more zones of the RF heating system according to variousembodiments of the present invention, particularly showing the articletrack and liquid spray nozzles;

FIG. 8 is a partial cutaway view of a helical conveyor disposed in avessel and suitable for use in one or more zones of the RF heatingsystem according to embodiments of the present invention, particularlyillustrating the helical travel path of the articles;

FIG. 9 is a partial perspective view of several components of a helicalconveyor according to various embodiments of the present invention,particularly illustrating components of an article-pushing assembly;

FIG. 10 is a partial schematic view of a processing zone employing ahelical conveyor according to various embodiments of the presentinvention, particularly illustrating elements of a liquid heat transfersystem for adjusting the temperature of the articles moving along thehelical conveyor;

FIG. 11 is a schematic side view of a pressure lock suitable for use intransitioning articles between environments having different pressuresaccording to various embodiments of the present invention, particularlyillustrating a wheel-type pressure lock;

FIG. 12 is a top cutaway view of a pressure lock suitable for use intransitioning articles between environments having different pressuresaccording to various embodiments of the present invention, particularlyillustrating a cylinder-type pressure lock;

FIG. 13 is a graphical representation of the average temperature at thegeometric center of articles being heated by an RF heating systemconfigured according to embodiments of the present invention as afunction of residence time particularly showing the relative residencetime in each area of the liquid contact zone depicted in FIG. 3;

FIG. 14 is a side cross-sectional view of an RF heating sectionconfigured according to various embodiments of the present invention,particularly illustrating the RF heating zone and RF energy transmissionsystem;

FIG. 15 is an axial cross-sectional view of the RF heating section takenalong line 15-15 in FIG. 14;

FIG. 16 is a schematic axial cross-section of an RF heating sectionparticularly illustrating the RF energy transmission system fortransmitting RF energy from the RF generator to the RF heating zone;

FIG. 17 is a schematic axial cross-section of an RF heating section,particularly illustrating one embodiment of a split RF applicator;

FIG. 18 is a schematic axial cross-section of an RF heating section,particularly illustrating another embodiment of a split RF applicator;

FIG. 19 is a simplified top view of a convey line suitable for use inthe RF heating section according to various embodiments of the presentinvention;

FIG. 20 is top cross-sectional view of an RF heating section configuredaccording to various embodiments of the present invention, particularlyillustrating a swing arm conveyor;

FIG. 21 is an axial cross-sectional view of the RF heating section shownin FIG. 20;

FIG. 22 is a simplified top view of an RF zone conveyor according tovarious embodiments of the present invention, particularly illustratingthe travel path of the article supporting members;

FIG. 23 is a partial perspective view of a portion of an RF zoneconveyor according to various embodiments of the present invention,particularly illustrating the movement of several article supportingmembers in a return orientation, transitioning from a return orientationto a heating orientation, and in a heating orientation;

FIG. 24 is a schematic top view of an article supporting memberconfigured according to embodiments of the present invention,particularly showing the article contact member and the connection ofthe article supporting member to the drive mechanism;

FIG. 25 is a partial perspective view of an article supporting memberconfigured according to various embodiments of the present invention;

FIG. 26 is an axial cross-sectional view of an article supporting memberconfigured according to various embodiments of the present invention,particularly illustrating various aspects of one type of article contactmember;

FIG. 27 is an axial cross-sectional view of another article supportingmember configured according to various embodiments of the presentinvention, particularly illustrating various aspects of another type ofarticle contact member;

FIG. 28 is a partial side view of an unloading zone in an RF heatingsection configured according to various embodiments of the presentinvention, particularly illustrating the transition between a swing armconveyor and a take-away conveyor in the unloading zone;

FIG. 29 is a partial side view of a loading zone in an RF heatingsection configured according to various embodiments of the presentinvention, particularly illustrating the transition between an approachconveyor and a swing-arm conveyor in the loading zone;

FIG. 30 is a schematic side view of a thermal isolation zone fortransitioning articles between an RF heating zone and a hold zoneaccording to various embodiments of the present invention;

FIG. 31 is a schematic cross-sectional view of several processing zonesin an RF heating system that include an indexing conveyor forintermittently transporting individual items through one of the zones,particularly when the indexing conveyor is a trough conveyor;

FIG. 32 is a schematic cross-sectional view of several processing zonesin an RF heating system that include an indexing conveyor forintermittently transporting individual items through one of the zones,particularly when the indexing conveyor is a helical conveyor; and

FIG. 33 is a schematic cross-sectional view of a hold zone and ahigh-pressure cooling zone, particularly illustrating variousembodiments of the present invention wherein each zone includes ahelical conveyor.

DETAILED DESCRIPTION

In many commercial processes, it can be desirable to heat large numbersof individual packaged articles in a rapid and uniform manner. Thepresent invention relates to systems and processes for such heating thatuse radio frequency (RF) energy to heat, or assist in heating, a varietyof different articles. Examples of the types of articles that can beprocessed according to the present invention include, but are notlimited to, packaged foodstuffs and beverages, as well as packagedpharmaceuticals, and packaged medical or veterinary fluids. The systemsdescribed herein may be configured for pasteurization, forsterilization, or for both pasteurization and sterilization. In general,pasteurization involves the rapid heating of an article or articles to aminimum temperature between about 60° C. and 100° C., or about 65° C. toabout 100° C., about 70° C. and 100° C., while sterilization involvesheating articles to a minimum temperature between 100° C. and 140° C.,or between 110° C. and 135° C., or between 120° C. and 130° C.

FIGS. 1-3 are overall diagrams of various embodiments of an RF heatingsystem 10 configured according to the present invention. As shown inFIGS. 1-3, articles introduced into the RF heating system 10 can passfrom a loading zone 12 into a liquid contact zone 14, wherein thearticles may be contacted with at least one liquid medium while beingheated to a temperature sufficient to pasteurize or sterilize thecontents of the package. The liquid contact zone 14 is the section ofthe RF heating system 10 located between where the articles areinitially contacted with a liquid medium, such as, for example, byspraying or submersion, and where the articles are finally removed fromcontact with a liquid medium. The articles may remain in contact withthe liquid medium while passing through the liquid contact zone 14. Asshown in FIG. 1, the liquid contact zone 14 may include an initialthermal regulation zone 16, an RF heating zone 18, and a subsequentthermal regulation zone 20. Specific configurations of the liquidcontact zone 14 are shown in FIG. 2 for an exemplary RF pasteurizationsystem and in FIG. 3 for an exemplary RF sterilization system, detailsof which will be discussed in further detail below. Once pasteurized orsterilized and after being cooled to a suitable handling temperature,the articles may be unloaded from the liquid contact zone 14 via anunloading zone 22.

In some embodiments, each of the initial thermal regulation zone 16, RFheating zone 18, and subsequent thermal regulation zone 20 may bedefined in a single vessel, while in other embodiments, at least one ofthese stages of the liquid contact zone 14 may be defined within one ormore separate vessels. Additionally, one or more transition zonesbetween individual processing stages or steps may also be defined in oneor more separate vessels, or one or more of those transition zones maybe defined within the same vessel as at least one preceding (e.g.,upline) or subsequent (e.g., downline) stage or zone.

In certain embodiments, the average residence time of each article inthe liquid contact zone 14, measured from the inlet to the initialthermal regulation zone 16 to the outlet of the subsequent thermalregulation zone 20, can be at least about 10, at least about 15, atleast about 20, at least about 25, at least about 30, at least about 35,at least about 40, at least about 45, at least about 50, at least about55, or at least about 60 minutes and/or not more than about 240, notmore than about 230, not more than about 220, not more than about 210,not more than about 200, not more than about 190, not more than about180, not more than about 170, not more than about 160, not more thanabout 150, not more than about 140, not more than about 130, not morethan about 120, not more than about 110, not more than about 100, notmore than about 90, not more than about 80, or not more than about 70minutes. When the articles are being pasteurized, each article can havea residence time in the liquid contact zone 14 in range of from about 10minutes to about 120 minutes, or about 30 minutes to about 70 minutes.When being sterilized, the articles can have an average residence timein the liquid contact zone 14 in the range of from about 20 minutes toabout 240 minutes, about 40 minutes to about 120 minutes, or about 60minutes to about 100 minutes.

The RF heating systems of the present invention may include at least oneconveyance system for transporting the articles along a travel paththrough one or more of the processing zones as described above. Theconveyance system may include a single convey line or it can include twoor more convey lines arranged in parallel or in series. Unlike othertypes of heating systems, the articles passed through the RF heatingsystems described herein are not placed in multi-article carriers, butinstead, travel through the system as individual sealed packages.Further, in certain embodiments, the articles passing through theinitial thermal regulation zone 16 and the subsequent thermal regulationzone 20 may not be in contact with or supported by any type of articlecontact member during passage through these zones.

One or more of the vessels defining the liquid contact zone 14 (e.g.,the initial thermal regulation zone 16, the RF heating zone 18, and/orthe subsequent thermal regulation zone 20) may be configured to be atleast partially liquid-filled. As used herein, the term “at leastpartially liquid-filled,” denotes a configuration in which at least 50percent of the total internal volume of a vessel is filled with aspecified liquid. In certain embodiments, at least about 60, at leastabout 70, at least about 80, at least about 90, at least about 95, or atleast about 99 percent of the total internal volume of one or morevessels may be filled with a liquid medium. While being passed through aliquid-filled vessel, the articles may be at least partially, orcompletely, submerged in the liquid medium during the processing step.When two or more vessels are at least partially filled with a liquidmedium, the liquid medium in one vessel may be the same as, or differentthan, the liquid medium in another adjacent vessel. Thus, articles thatare at least partially submerged in one liquid during the processingstep performed in one zone may be at least partially submerged in thesame or in a different liquid during the processing step performed in aprevious or subsequent zone. In certain embodiments, the initial thermalregulation zone 16, the RF heating zone 18, and the subsequent thermalregulation zone 20 are configured to maintain the articles insubstantially continuous contact with a liquid medium.

The liquid medium used in the vessel or vessels of the liquid contactzone 14 can be any suitable non-compressible fluid that exists in aliquid state at the operating conditions within the vessel. The liquidmedium may have a dielectric constant greater than the dielectricconstant of air. In some cases, the liquid medium may have a dielectricconstant similar to the dielectric constant of the packaged substancebeing processed. For example, the dielectric constant of the liquidmedium may be at least about 20, at least about 25, at least about 30,at least about 35, or at least about 40 and/or not more than about 120,not more than about 110, not more than about 100, not more than about80, or not more than about 70, measured at a temperature of 80° C. and afrequency of 100 MHz. Water (or a liquid comprising water) may beparticularly suitable for systems used to heat ingestible substancessuch as foodstuffs and medical or pharmaceutical fluids. Additives suchas, for example, oils, alcohols, glycols, or salts, may be optionally beadded to the liquid medium to alter or enhance its physical properties(e.g., boiling point) during processing, if needed.

Several different types of articles may be heated using RF heatingsystems of the present invention. Typically, each article includes asealed package surrounding at least one ingestible substance. Examplesof ingestible substances can include, but are not limited to, food,beverages, medical, or pharmaceutical items suitable for human and/oranimal consumption. A packaged article may include a single type offoodstuff (or other ingestible substance), or it may include two or moredifferent ingestible substances, which may be in contact with each otheror separated from one another within the package. The total volume offoodstuff (or other ingestible substance) within each sealed package canbe at least about 4, at least about 6, at least about 8, at least about10, at least about 15, at least about 20, at least about 25, at leastabout 50, at least about 75, at least about 100, at least about 150, atleast about 200, or at least about 250 cubic inches and/or not more thanabout 500, not more than about 400, not more than about 300, not morethan about 200, not more than about 100, not more than about 75, notmore than about 50, not more than about 25, not more than about 24, notmore than about 22, not more than about 18, or not more than about 16cubic inches.

In certain embodiments, the article, foodstuff, or other ingestiblesubstance being heated may have a dielectric constant of at least about20 and not more than about 150. Additionally, or in the alternative, thefoodstuff or other ingestible substance may have a dielectric lossfactor of at least about 10 and not more than about 1500. Unlessotherwise noted, the dielectric constant and dielectric loss factorsprovided herein are measured at a frequency of 100 MHz and a temperatureof 80° C. In other embodiments, the foodstuff or other ingestiblesubstance can have a dielectric constant of at least about 25, at leastabout 30, at least about 35, or at least about 40 and/or not more thanabout 140, not more than about 130, not more than about 120, not morethan about 110, not more than about 100, not more than about 90, notmore than about 80, not more than about 70, or not more than about 60,or it can be in the range of from about 20 to about 150, about 30 toabout 100, or about 40 to about 60. Additionally, the foodstuff or otheringestible substance can have a dielectric loss factor of at least about10, at least about 25, at least about 50, at least about 100, at leastabout 150, or at least about 200 and/or not more than about 1500, notmore than about 1250, not more than about 1000, or not more than about800, or it can be in the range of from about 10 to about 1500, about 100to about 1250, or about 200 to about 800.

The packages used to hold the foodstuff or other ingestible substancemay be of any size and/or shape. In some embodiments, each package canhave a length (longest dimension) of at least about 2, at least about 4,at least about 6, at least about 8 inches and/or not more than about 30,not more than about 20, not more than about 18, not more than about 15,not more than about 12, not more than about 10, or not more than about 8inches; a width (second longest dimension) of at least about 1 inch, atleast about 2, or at least about 4 inches and/or not more than about 20,not more than about 15, not more than about 12, not more than about 10,or not more than about 8 inches; and a depth (shortest dimension) of atleast about 0.5, at least about 1, or at least about 2 inches and/or notmore than about 8, not more than about 6, or not more than about 4inches. The packages may be formed of materials that include, but arenot limited to, plastics, cellulosics, glass, and combinations thereof.In certain embodiments, the packages are rigid or semi-rigid, but notflexible. In other embodiments, the packages can be flexible, orpartially flexible.

The RF heating systems of the present invention may be configured tomaximize spatial efficiency, while still achieving desirable levels ofproduction. For example, the convey line or lines may be configured suchthat each article may travel along a path between the inlet and outletof the liquid contact zone 14 that is at least about 300, at least about400, at least about 500, at least about 600, at least about 700, atleast about 800, at least about 900, at least about 1000, at least about1250, or at least about 1500 feet and/or not more than about 25,000, notmore than about 22,500, not more than about 20,000, not more than about17,500, not more than about 15,000, not more than about 12,500, not morethan about 10,000, not more than about 7500, not more than about 6000,or not more than about 5000 feet, or the travel path of the articlethrough the liquid contact zone 14 can be in the range of from about 500feet to about 25,000 feet or from about 600 feet to about 6000 feet. Itshould be understood that the travel path through the liquid contactzone 14 is equal to the sum of the length of the travel paths in theinitial thermal regulation zone 16, the RF heating zone 18, and thesubsequent thermal regulation zone 20, along with the travel pathsthrough any transition zones therebetween.

In some embodiments, the liquid contact zone 14 can be configured sothat the travel path of the articles through the liquid contact zone 14can be at least 2, at least about 5, at least about 8, at least about10, at least about 12, at least about 15, at least about 18, at leastabout 20, at least about 22, or at least about 25 times greater than thelinear distance between the inlet and outlet of the liquid contact zone14. In such cases, the article travel paths (or convey lines definingthe travel paths) may be nonlinear. Examples of the liquid contact zones14 that include such nonlinear travel paths 60 for articles 100 areshown in FIGS. 4-6. In FIGS. 4-6, the travel paths 60 are shown withsolid lines, while the linear distance between the inlet 62 and outlet64 of the liquid contact zones 14 are shown as dashed lines.

When the liquid contact zone includes an initial thermal regulationzone, an RF heating zone, and a subsequent thermal regulation zone, theinlet 62 shown in FIGS. 4-6 can be the inlet to the initial thermalregulation zone, and the outlet 64 can be the outlet of the subsequentthermal regulation zone. In certain embodiments, the maximum lineardistance between any two points on the article travel path through theliquid contact zone 14 can be not more than about 500, not more thanabout 450, not more than about 400, not more than about 350, not morethan about 300, not more than about 250, not more than about 200, notmore than about 150, not more than about 100, or not more than about 50feet.

As a result, the RF heating systems of the present invention may beconfigured to have a relatively small footprint such that, in certainembodiments, the entire liquid contact zone 14 of the RF heating systemmay be capable of fitting into a single cuboid having a total volume ofnot more than about 400,000, not more than about 350,000, not more thanabout 300,000, not more than about 250,000, not more than about 200,000,not more than about 150,000, not more than about 100,000, not more thanabout 75,000, or not more than about 50,000 cubic feet.

At the same time, the RF heating systems as described herein may beconfigured to achieve an overall production rate of at least about 2, atleast about 5, at least about 10, at least about 15, at least about 20,at least about 25, at least about 30, at least about 35, at least about40, at least about 45, at least about 50 articles per minute(articles/min) and/or not more than about 500, not more than about 450,not more than about 400, not more than about 350, not more than about300, not more than about 250, not more than about 200 articles/min. Inother embodiments, the mass convey rate of the food (or other ediblesubstance) passing through the RF heating system can be at least about1, at least about 5, at least about 10, at least about 15, at leastabout 20, or at least about 25 pounds of food (or other ediblesubstance) per minute (lb/min) and/or not more than about 500, not morethan about 450, not more than about 400, not more than about 350, notmore than about 300, not more than about 250, not more than about 200,not more than about 150 lb/min.

Turning back to FIGS. 1-3, the articles may be initially introduced intoa loading zone 12. The loading zone 12 may include any suitable deviceor system capable initially contacting one or more articles with aliquid medium. This contacting may include, for example, spraying thearticles with or at least partially submerging the articles in theliquid medium. In certain embodiments, the articles introduced into theloading zone 12 may have an average temperature, measured at thegeometric center of each article, of at least about 5, at least about10, at least about 15, at least about 20, at least about 25, or at leastabout 30° C. and/or not more than about 70, not more than about 60, notmore than about 50, not more than about 40, or not more than about 30°C. As used herein, the “geometric center” of an article is the commonpoint of intersection of planes passing through the midpoints of thearticle's length, width, and height. The loading zone may be operated atapproximately ambient temperature and/or pressure.

As shown in FIGS. 1-3, the articles may then be passed from a loadingzone 12 into the initial thermal regulation zone 16 of the liquidcontact zone 14. When introduced into the initial thermal regulationzone 16, the average temperature at the geometric center of the articlescan be at least about 5, at least about 10, at least about 15, at leastabout 20, at least about 25, or at least about 30° C. and/or not morethan about 90, not more than about 80, not more than about 70, not morethan about 60, not more than about 50, or not more than about 40° C. Forpasteurization systems, the temperature at the geometric center of thearticles introduced into initial thermal regulation zone 16 may be inthe range of from about 5° C. to about 70° C. or about 25° C. to about40° C., while it may be in the range of from about 15° C. to about 90°C. or about 30° C. to about 60° C. for sterilization systems.

In certain embodiments, the initial thermal regulation zone 16 may beconfigured to increase the temperature of each article, measured at itsgeometric center, by at least about 1, at least about 5, at least about10, at least about 15, or at least about 20° C. and/or not more thanabout 60, not more than about 55, not more than about 50, not more thanabout 45, not more than about 40, not more than about 35, or not morethan about 30° C., or it can be increased by an amount in the range offrom about 1° C. to about 60° C. or about 10° C. to about 30° C. Incertain embodiments, the average temperature at the geometric center ofthe articles exiting the initial thermal regulation zone 16 may be atleast about 25, at least about 30, at least about 35, at least about 40,at least about 45, at least about 50, at least about 55, or at leastabout 60° C. and/or not more than about 90, not more than about 85, notmore than about 80, not more than about 75, not more than about 70, ornot more than about 65° C. During pasteurization, the averagetemperature at the geometric center of the articles exiting the initialthermal regulation zone 16 can be in the range of from about 25° C. toabout 90° C. or about 40° C. to about 70° C., while it may be in therange of from about 40° C. to about 90° C., or about 60° C. to about 80°C. during sterilization.

Additionally, the initial thermal regulation zone 16 may be configuredto regulate the temperature of the articles passing therethrough topromote temperature uniformity amongst the articles. For example, incertain embodiments, the temperature of the articles may be regulatedwithin the initial thermal regulation zone 16 so that the average valueof the difference between the maximum temperature (i.e., hottestportion) and the minimum temperature (i.e., coldest portion) of eacharticle exiting the initial thermal regulation zone 16 can be not morethan about 20, not more than about 15, not more than about 10, more thanabout 5, not more than about 4, not more than about 2.5, not more thanabout 2, not more than about 1.5, not more than about 1, or not morethan about 0.5° C. Similar differences can be achieved between theaverage of the temperatures of adjacent articles removed from theinitial temperature regulation zone 16, measured at the geometric centerof each article.

In certain embodiments, the articles can have an average residence timein the initial thermal regulation zone 16 of at least about 10, at leastabout 15, at least about 20, or at least about 25 minutes and/or notmore than about 70, not more than about 65, not more than about 60, notmore than about 55, not more than about 50, not more than about 45, ornot more than about 40 minutes, or it can be in the range of from about10 to about 70 minutes, or about 25 to about 40 minutes. This cancorrespond to, for example, at least about 10, at least about 15, atleast about 20, at least about 25, or at least about 30 percent and/ornot more than about 75, not more than about 70, not more than about 65,not more than about 60, not more than about 55, not more than about 50,not more than about 45 percent of the total residence time of thearticle within the entire liquid contact zone 14.

In certain embodiments, at least about 15, at least about 20, at leastabout 25, or at least about 30 percent and/or not more than about 75,not more than about 70, not more than about 65, not more than about 60,not more than about 55, or not more than about 50 percent of the totaltravel path along which the articles are transported through the RFheating system may be defined within the initial thermal regulation zone16. In some cases, the travel path of the articles through the initialthermal regulation zone 16 can correspond to 15 percent to 75 percent or30 percent to 55 percent of the total travel path of the articlesthrough the entire RF heating system.

As shown in FIGS. 2 and 3, whether the RF heating system is configuredfor pasteurization or sterilization, the initial thermal regulation zone16 may include a thermal equilibration zone 24 followed by an optionalpressure lock 26. The thermal equilibration zone 24 may be configured toincrease the temperature of the articles passing therethrough in orderto promote temperature uniformity within each article and amongst thearticles passing therethrough, as described previously. In certainembodiments, articles passing through the thermal equilibration zone 24may be contacted with a liquid during at least a portion of the thermalequilibration step. The liquid may comprise or be water and can have atemperature within about 25, within about 20, within about 15, or withinabout 10° C. of the average temperature at the geometric center of thearticles introduced into the thermal equilibration zone 24.

The contacting may be performed by any suitable method including, butnot limited to, by spraying the articles with and/or by submerging, orpartially submerging, the articles in the liquid medium. In someembodiments, the thermal equilibration zone 24 may further include oneor more liquid jets for discharging streams of pressurized liquid towardthe articles. Such pressurization may increase the Reynolds number ofthe liquid surrounding the article, thereby enhancing heat transfer.When present, the liquid jets may be positioned along or more walls ofthe vessel in which the thermal equilibration step is performed and maybe used whether or not the articles are additionally submerged in aliquid medium.

The articles may be passed through the thermal equilibration zone 24 viaa conveyance system. Examples of suitable types of conveyance systemscan include, but are not limited to, plastic or rubber belt conveyors,chain conveyors, roller conveyors, flexible or multi-flexing conveyors,wire mesh conveyors, bucket conveyors, pneumatic conveyors, troughconveyors, vibrating conveyors, and combinations thereof. The conveyancesystem may include a single convey line, or two or more convey linesarranged within the vessel or vessels defining the thermal equilibrationzone.

In certain embodiments, the thermal equilibration zone 24 may include atleast one helical conveyor. One example of a helical conveyor suitablefor use in the thermal equilibration zone 24 of an RF heating systemconfigured according to embodiments of the present invention is shown inFIGS. 7 through 10.

Turning now to FIGS. 7 through 10, a helical conveyor 260 configuredaccording to embodiments of the present invention is shown. Helicalconveyor 260 includes a track 262 configured to guide articles 100 alonga convey pathway. At least a portion of the track 262 (FIGS. 7 and 8)forms a substantially helical path 248 (FIG. 10) that extends around asubstantially vertical central axis 263. The helical path formed by thetrack 262 shown in FIGS. 7 and 8 includes a plurality ofvertically-spaced tiers 264 spaced apart from one another in a directionparallel to the vertical central axis 263. In total, the portion of thetrack 262 forming the helical pathway 248 can include at least 3, atleast 5, at least 8, at least 10, at least 12, at least 15, or 20 ormore vertically-spaced tiers 264 and/or not more than 100, not more than75, not more than 50, not more than 40, not more than 35, not more than30, not more than 25, or not more than 18 vertically-spaced tiers 264.

As shown in FIGS. 8 and 9, the helical conveyor 260 can have a pluralityof article pusher members 270 for contacting the articles 100 so thateach article 100 can be moved along the portion of the track 262 thatdefines the helical path. In some embodiments, one or more of thearticle pusher members 270 may be configured to rotate relative to thetrack 262, while, in other embodiments, at least a portion of the track262 may be configured to rotate relative to the article pusher members270 on the central vertical axis 263 of the conveyor 260.

As particularly shown in FIGS. 7 and 8, the portion of the track 262that forms the helical pathway may comprise an outer section 266 and aninner section 268 spaced inwardly toward the central vertical axis 263from the outer section 266. In certain cases, a gap 267 can be formedbetween the outer section 266 and inner section 268 and the gap 267 mayextend along a portion, or substantially all, of the helical path. Incertain embodiments, the article pusher members 270 can extend throughat least a portion of the gap 267 formed between the outer section 266and inner section 268 of the track 262. Each article pusher member 270may include at least one vertical rod and, in some cases, may include apair of vertical rods spaced radially spaced apart from one another, asshown in FIG. 8. As shown in FIGS. 8 and 9, each of the article pushermembers 270 extends to a plurality of the vertically-spaced tiers 264and can be configured to simultaneously contact two or more articles 100located on different tiers 264 of the track 262. Thus, two or morearticles 100 located on different vertical tiers may be contacted with acommon article pusher member 270.

When the article pusher members 270 are configured to move relative tothe track, the helical conveyor 260 may further comprise an articlepushing assembly 280, as particularly shown in FIG. 8. The articlepushing assembly 280 may include a central drive shaft 282, the articlepusher members 270, and a plurality of connectors 284 for connecting thearticle pusher members 270 to the central drive shaft 282. In certainembodiments, the connectors 284 may include at least an upper connectionwheel 286 and a lower connection wheel 288 as shown in FIG. 9. The upperconnection wheel 286 and/or the lower connection wheel 288 may include ahub 272 coupled to the central drive shaft 282, a rim 274 coupled to thearticle pusher members 270, and a plurality of radially-extending spokes276 connecting the hub 272 to the rim 274. As shown in FIG. 9, the upperportions of each of the article pusher members 270 may be coupled to therim 274 of the upper connection wheel 286, while the lower portion ofthe article pusher members 270 may be coupled to the rim 274 of thelower connection wheel 288. In some embodiments, the connectors 284 mayfurther include a plurality of rollers 290 for supporting the lowerconnection wheel 288 permitting the lower connection wheel 288 to rotateas the central drive shaft 282 rotates about the central vertical axis263. As shown in the embodiment depicted in FIG. 9, when the centraldrive shaft 282 does not extend to the lower portion of the articlepushing assembly 280, the lower connection wheel 288 may not include anyspokes.

As also shown in FIG. 9, the helical conveyor 260 can include anactuator 292 coupled to the central drive shaft 282 and configured tocause the central drive shaft 282 to rotate on the central vertical axis263. In some embodiments, the actuator 292 may be located within thevessel 250 that houses the helical conveyor 260, while, in otherembodiments, actuator 292 may be positioned outside the vessel 250 asshown in FIG. 9.

In operation, the articles 100 may be pushed along the track 262 byintermittently rotating the article pushing assembly 280 using theactuator 292. As the actuator 292 causes the central drive shaft 282 torotate, the central drive shaft 282 causes the upper connection wheel286 and/or the lower connection wheel 288 to rotate, which also causesthe article pusher members 270 to rotate relative to the track 262. Asthe article pusher members 270 move through the gap 267 between theouter section 266 and inner section 268 of the track 262, the articlepusher members 270 contact one or more articles 100 on the same and/or adifferent vertical tier and push the articles 100 along the helical pathdefined by the track 262.

In certain embodiments, the movement of the article pushing assembly 280can be constant. In other embodiments, the movement of the articlepushing assembly 280 may be intermittent, so that, for example, thearticles 100 are passed along the track 262 in an intermittent manner.In such a way, the residence time of the articles 100 may be modifiedby, for example, adjusting the magnitude of the intermittent movement ofthe article pushing assembly 280. In certain embodiments, the magnitudeof the intermittent movement of the article pushing assembly 280 can bemeasured by the angular magnitude of the intermittent rotation. Byincreasing (or decreasing) the magnitude of the angular rotation of thearticle pushing assembly 280 without changing the rate at which thearticles 100 are loaded onto or unloaded from the track 262 (e.g., theloading or unloading rates), the residence time of the articles 100along the helical path can be adjusted in indirect proportion to thechange in the magnitude of angular rotation. That is, larger changes inthe angular magnitude of intermittent rotation results in shorterresidence times, and vice versa. Additional details relating specificmethods of adjusting the residence time of articles on an intermittentconveyor (including a helical conveyor) are discussed below.

As particular shown in FIGS. 8 and 10, the helical conveyor 260 may bereceived inside a pressure vessel 250 having an inlet 252 configured toreceive articles 100 into the vessel 250 and an outlet 254 fordischarging the articles 100 from the vessel 250. The helical conveyor260 shown in FIG. 10 is depicted schematically and primarily illustratesthe helical path 248 along which the articles 100 travel when beingpassed along the track of the helical conveyor. As shown in FIG. 10, thehelical conveyor 260 may be operable to transport the articles 100 awayfrom the inlet 252 toward the outlet 254 of the vessel 250 along thehelical path 248. Although shown as being configured to transportarticles 100 upwardly from a lower inlet 252 to an upper outlet 254, theconveyor 260 may be configured to transport articles 100 downwardly froman upper inlet to a lower outlet, or the inlet and outlet may be atapproximately the same vertical elevation if, for example, two helicalconveyors are arranged in series in a single vessel.

As the articles 100 pass along the helical path 248 of the helicalconveyor 260, at least a portion of the articles 100 may be contactedwith a liquid medium. The step of contacting the articles 100 with aliquid medium may include submerging the articles 100 in a liquid mediumand/or spraying the liquid medium onto the articles 100. The liquidmedium may act as a liquid heat transfer medium for facilitating heatingor cooling of the article 100. When the helical conveyor 260 is utilizedin the thermal equilibration zone 24, the liquid heat transfer mediummay be warmed liquid for increasing the temperature of the articles 100being contacted. In other embodiments, one or more of the hold zone 30,high-pressure cooling zone 32, and low-pressure cooling zone 34 may alsoinclude at least one helical conveyor and the liquid medium, whenpresent, in each of those zones may be heated or cooled in order tofacilitate the desired transfer of heat to or from the article 100.

The thermal equilibration zone 24 (or any of the hold zone 30,high-pressure cooling zone 32, or low-pressure cooling zone 34 thatinclude a helical conveyor) can further include a liquid heat transfersystem for adjusting the temperature of the articles 100 in the vesselby contact with a liquid heat transfer medium. As particularly shown inFIG. 10, the heat transfer system 240 includes a thermal regulator 242to adjust the temperature of the heat transfer medium introduced intothe vessel 250 and a circulation pump 244 for pumping the heat transferliquid from a liquid outlet 251 of the vessel 250, through the thermalregulator 242, and back into the vessel 250 via a liquid inlet 253. Incertain embodiments, the liquid inlet 253 can be a single inlet fordischarging liquid into a pool of liquid in which the articles 100 aresubmerged, as generally shown in FIG. 10. In other embodiments, theliquid inlet can comprise a plurality of spray nozzles 253 fordischarging streams of pressurized heat transfer medium toward thearticles 100 moving along the helical path. In some cases, a pluralityof spray nozzles 253 may be spaced apart from one another along one ormore vertically-elongated manifolds 255 disposed proximate the outersection 266 and/or inner section 268 of the track 262 of the helicalconveyor 260. One example of a possible orientation of such manifolds255 is shown in FIG. 7.

The specific type of thermal regulator 242 used in the liquid heattransfer system 240 may depend on whether the liquid heat transfermedium is used to heat or cool the articles 100. In some embodiments,the thermal regulator 242 can be a heater configured to increase thetemperature of the heat transfer medium withdrawn from the vessel 250via the liquid outlet 251 prior to its reintroduction into the vesselvia a liquid inlet 253. In other embodiments, the thermal regulator 242can be a cooler configured to reduce the temperature of the heattransfer medium flowing from the liquid outlet 251 of the vessel 250into the liquid inlet 253. In certain embodiments, the liquid heattransfer system 240 may include both a heater and a cooler. Any suitabletype of heat exchanger may be used as a thermal regulator 242 including,but not limited to, a shell-and-tube heat exchangers, plate heatexchangers, plate and shell heat exchangers, plate fin heat exchangers,and combinations thereof.

Turning back to FIGS. 2 and 3, the articles exiting the thermalequilibration zone 24 can have an average temperature, measured at thegeometric center of the articles, of at least about 25, at least about30, at least about 35, at least about 40, at least about 45, at leastabout 50, at least about 55, or at least about 60° C. and/or not morethan about 90, not more than about 85, not more than about 80, not morethan about 75, not more than about 70, or not more than about 65° C.When the articles are being pasteurized, the average temperature at thegeometric center of the articles exiting the thermal equilibration zone24 can be in the range of from about 25° C. to about 90° C. or about 40°C. to about 70° C., while it may be in the range of from about 40° C. toabout 90° C., or about 60° C. to about 80° C. when the articles arebeing sterilized. The heated articles may also have a substantiallyuniform temperature such that, for example, the temperature at thegeometric center of adjacent articles exiting the thermal equilibrationzone 24 can be within about 10, within about 8, within about 6, withinabout 4, within about 2, within about 1.5, within about 1, or withinabout 0.5° C. of one another.

As shown in FIGS. 2 and 3, after exiting the thermal equilibration zone24 of the initial thermal regulation zone 16, the articles may then bepassed through a pressure lock 26 a before entering the RF heating zone18. In general, a pressure lock can be any device suitable fortransitioning the articles between two environments having differentpressures. Pressure locks may transition the articles from ahigher-pressure environment to a lower-pressure environment or from alower-pressure environment to a higher-pressure environment. In certainembodiments, pressure lock 26 a may be configured to transition thearticles from the lower-pressure thermal equilibration zone 24 to thehigher-pressure RF heating zone 18. In certain embodiments, the RFheating zone 18 can have a pressure that is at least about 2, at leastabout 5, at least about 10, or at least about 15 psig and/or not morethan about 50, not more than about 40, not more than about 30, not morethan about 20, or not more than about 10 psig higher than the pressurein the thermal equilibration zone 24.

Turning now to FIG. 11, one embodiment of a pressure lock 126 suitablefor use in RF heating systems of the present invention is shown. Asdepicted in FIG. 11, the pressure lock 126 includes an outer cylinder120, an inner cylinder 122, and a plurality of dividers 124 extendingbetween the inner cylinder 122 and the outer cylinder 120. The dividers124 define a plurality of article-receiving spaces 128, into which oneor more articles 100 may be placed. As shown in FIG. 11, one or morearticles 100 may be loaded from an entrance convey line 130 into anarticle receiving space 128 of the pressure lock 126. Once the article100 is loaded into the article-receiving space 128, the inner and outercylinders 120, 122 of the pressure lock 126 rotate, as shown by thearrows in FIG. 11, so that the previously-loaded article-receiving space128 moves away from the entrance convey line 130 located in a firstpressure vessel 140 and toward an exit convey line 132 located in asecond pressure vessel 142 having a different pressure than the firstpressure vessel 140. This permits another article 100 to be loaded intothe adjacent open article-receiving space 128, after which the pressurelock 126 again rotates to move the articles 100 away from the entranceconvey line 130 and toward the exit convey line 132. Once the article100 in the article receiving space 128 reaches the exit convey line 132,it may be unloaded from the pressure lock 126 onto exit convey line 132and passed to the next processing zone (not shown).

Another embodiment of a pressure lock 226 suitable for use in RF systemsof the present invention is shown in FIG. 12. The pressure lock 226shown in FIG. 12 includes a loading area 220, an unloading area 222, anda transfer chamber 224 that extends between the loading area 220 and theunloading area 222. A movable transport cylinder 216 is disposed in thetransport chamber 224. The transport cylinder 216 includes an opening227 extending therethrough and configured to receive at least onearticle 100 from the loading area 220 and transport it to the unloadingarea 222. The opening 227 in the transport cylinder 216 includes aninlet 228 and an outlet 230. A plurality of sealing rings 232 can becoupled to outside of the transport cylinder 216 for fluidly isolatingone side of the transport cylinder 216 from the other side, whichpermits the articles 100 to be transported in the opening 227 of thetransport cylinder 216 from the lower-pressure loading zone 220 to thehigher-pressure unloading zone 222. In certain embodiments, theunloading zone 222 may be disposed within a pressure vessel, while theloading zone 220 may be located outside the pressure vessel 250.

In operation, one or more articles 100 may be loaded into the inlet 228of the transport cylinder 216 using a loading device, such as a pusherarm 234 shown in FIG. 12. Once loaded into the transport cylinder 216,the article or articles 100 may be transported, while in the opening 227of the transport cylinder 216, from the loading area 220 to theunloading area 222 along a travel path 236 that can be substantiallyperpendicular to the direction of extension 237 of the vessel into whichthe articles 100 are introduced. Once in unloading zone 222, anunloading device, shown as pusher arm 238, may be used to unload thearticles 100 via the outlet 230 of the transport cylinder 216 and ontoanother convey line 240. Convey line 240 may subsequently pass thearticles 100 onto the next downline processing zone (not shown in FIG.12).

Although shown in FIG. 12 as having a single transport chamber 224,pressure lock 226 may also include one or more additional transportchambers located on the same or opposite sides of the vessel. In someembodiments, the pressure lock 226 may further include another loadingzone similar to the loading zone 220 shown in FIG. 12, but located onthe opposite side of the vessel 250. In such cases, the transportcylinder 216 could be alternately movable between the two lower-pressureloading zones and the higher-pressure unloading zone in a similar manneras described above. Additionally, in some embodiments, each cylinder 216could have more than one article-receiving opening 227 configured toreceive at least one article 100 from the loading area 220 and transportit to the unloading area 222.

Referring again to FIGS. 2 and 3, articles exiting the pressure lock 26a may be introduced into the RF heating zone 18 defined within an RFapplicator (not shown in FIG. 2 or 3). In RF heating zone 18, thearticles may be rapidly heated via exposure to RF energy. As usedherein, the term “RF energy” or “radio frequency energy” refers toelectromagnetic energy having a frequency of greater than 300 kHz andless than 300 MHz. In certain embodiments, the RF heating zone 18 canutilize RF energy having a frequency of at least about 500 kHz, at leastabout 1 MHz, at least about 5 MHz, at least about 10 MHz, at least about20 MHz, at least about 30 MHz, at least about 40 MHz, or at least about50 MHz. Additionally, or in the alternative, the RF heating zone 18 mayutilize RF energy having a frequency of not more than about 250 MHz, notmore than about 200 MHz, or not more than about 150 MHz. The frequencyof the RF energy utilized in the RF heating zone 18 can be in the rangeof from 50 to 150 MHz.

In addition to RF energy, the RF heating zone 18 may optionally utilizeone or more other types of heat sources such as, for example, conductiveor convective heat sources, or other conventional heating methods ordevices. However, at least about 35, at least about 45, at least about55, at least about 65, at least about 75, at least about 85, at leastabout 95 percent, or substantially all, of the energy used to heat thearticles within the RF heating zone 18 can be derived from an RF energysource. In some embodiments, not more than about 50, not more than about40, not more than about 30, not more than about 20, not more than about10, or not more than about 5 percent or substantially none of the energyused to heat the articles in the RF heating zone 18 may be provided byother heat sources, including non-RF electromagnetic radiation having afrequency greater than 300 MHz.

The articles passing through the RF heating zone 18 may be at leastpartially submerged in a liquid medium while being heated with RF energyduring at least a portion of the heating step. In some embodiments, theliquid medium may be the same liquid medium in which the articles weresubmerged while passing through the initial thermal regulation zone 16.The RF heating zone 18 may be at least partially defined within apressurized vessel so that the RF heating zone 18 is maintained at apressure of at least about 2, at least about 5, at least about 10, or atleast about 15 psig and/or not more than about 80, not more than about75, not more than about 70, not more than about 65, not more than about60, not more than about 55, not more than about 50, not more than about45, not more than about 40, not more than about 35, not more than about30, not more than about 25, not more than about 20 psig during theheating step. When the articles passing through the RF heating zone 18are being pasteurized, the pressure in the RF heating zone 18 may be inthe range of from about 1 psig to about 40 psig or about 2 psig to about20 psig. When the articles passing through the RF heating zone 18 arebeing sterilized, the pressure in the RF heating zone 18 may be in therange of from about 5 psig to about 80 psig, or about 15 psig to about40 psig.

In certain embodiments, the RF heating zone 18 may be configured to heatthe articles passing therethrough so that the temperature of thegeometric center of the articles increases by at least about 10, atleast about 15, at least about 20, at least about 25, at least about 30,at least about 35, at least about 40, or at least about 45° C. and/ornot more than about 120, not more than about 110, not more than about100, not more than about 90, not more than about 85, not more than about80, not more than about 75, not more than about 70, not more than about65, not more than about 60, not more than about 55, not more than about50, not more than about 45, or not more than about 40° C. When thearticles are being pasteurized, the RF heating zone 18 may be configuredto increase the temperature of the geometric center of the articles byan amount in the range of from about 10° C. to about 60° C. or about 20°C. to about 40° C. When the articles are being sterilized, the RFheating zone may be configured to increase the temperature of thegeometric center of the articles by an amount in the range of from about20° C. to about 120° C. or about 35° C. to about 65° C.

The temperature at the geometric center of the articles introduced intothe RF heating zone 18 can be at least about 25, at least about 30, atleast about 35, at least about 40, at least about 45, at least about 50,at least about 55, or at least about 60° C. and/or not more than about110, not more than about 105, not more than about 100, not more thanabout 95, not more than about 90, not more than about 85, not more thanabout 80, not more than about 75, not more than about 70° C. When thearticles are being pasteurized, the temperature at the geometric centerof the articles introduced into the RF heating zone 18 can be in therange of from about 25° C. to about 90° C. or about 40° C. to about 70°C., while articles being sterilized may have a temperature at thegeometric center of the articles in the range of from about 40° C. toabout 110° C. or about 60° C. to about 90° C. when entering the RFheating zone 18.

The articles introduced into the RF heating zone 18 may be heated to thedesired temperature in a relatively short period of time. In some cases,this may help minimize damage or degradation of the foodstuff or otheringestible substance being heated. In certain embodiments, the articlespassed through RF heating zone 18 may have an average residence time inthe RF heating zone 18 (also called an RF heating period) of at leastabout 0.1, at least about 0.25, at least about 0.5, at least about 0.75,at least about 1, at least about 1.25, or at least about 1.5 minutesand/or not more than about 6, not more than about 5.5, not more thanabout 5, not more than about 4.5, not more than about 4, not more thanabout 3.5, not more than about 3, not more than about 2.5, not more thanabout 2, not more than about 1.5, or not more than about 1 minute. Whenthe articles are being pasteurized, the average residence time of eacharticle in the RF heating zone 18 may be in the range of from about 0.1minutes to 3 minutes, or 0.5 minutes to 1.5 minutes. When the articlesare being sterilized, each article may have an average residence time inthe range of from about 0.5 minutes to about 6 minutes, or about 1.5minutes to about 3 minutes.

FIG. 13 provides a graphical depiction of the change in temperature atthe geometric center of the articles as the articles are passed througheach stage of the liquid contact zone as a function of residence time.As shown in FIG. 13, although the articles may pass through the RFheating zone 18 relatively quickly, the energy provided to the articlesin the RF heating zone 18 is sufficient increase the temperature of thearticles rapidly, thereby ensuring that pasteurization or sterilizationoccur with minimal degradation of the foodstuff or other ingestiblesubstance. For example, in certain embodiments, the overall heating rateof the articles passing through the RF heating zone 18 can be at leastabout 5, at least about 10, at least about 15, or at least about 20°C./min and/or not more than about 90, not more than about 85, not morethan about 80, not more than about 75, not more than about 70, not morethan about 65, not more than about 60, not more than about 55, not morethan about 50, not more than about 45, not more than about 40, not morethan about 35, or not more than about 30° C./min, measured at thegeometric center of the articles. In some embodiments, the overallheating rate measured at the geometric center of the articles passingthrough the RF heating zone 18 can be in the range of from about 5°C./min to about 80° C./min or about 10° C./min to about 30° C./min.

As shown by comparing the relative residence time of the articles ineach of processing zones shown in FIG. 13, the residence time of thearticles in the RF heating zone 18 is only a small percentage of thetotal residence time of the articles passing through liquid contact zone14. For example, in some embodiments, the average residence time of thearticles in the RF heating zone 18 can be not more than about 10, notmore than about 8, not more than about 6, not more than about 5, or notmore than about 4 percent of the average residence time of the articlesin the liquid contact zone 14. Additionally, the average residence timeof the articles in the RF heating zone 18 can be at least about 0.25, atleast about 0.5, at least about 0.75, at least about 1, at least about1.25, or at least about 1.5 percent of the average residence time of thearticles in the liquid contact zone 14, or it can be in the range offrom about 0.25 percent to about 10 percent or about 1.5 percent toabout 4 percent of the average residence time of the articles in theliquid contact zone 14. In some cases, the length of the total travelpath of the articles through the RF heating zone 18 can be not more thanabout 30, not more than about 25, not more than about 20, not more thanabout 15, not more than about 10, not more than about 5, or not morethan about 3 feet.

As also shown in FIG. 13, the articles passing through liquid contactzone 14 may spend far less time in the RF heating zone 18 than in theinitial thermal regulation zone 16. For example, in certain embodiments,the average residence time of the articles passing through the RFheating zone 18 can be not more than about 30, not more than about 25,not more than about 20, not more than about 15, not more than about 10,not more than about 6, or not more than about 5 percent of the averageresidence time of the articles passing through the initial thermalregulation zone 16. In some cases, the average residence time of thearticles passing through the RF heating zone 18 can be at least about0.50, at least about 1, at least about 1.5, at least about 2, at leastabout 2.5, at least about 3, at least about 3.5, at least about 4, atleast about 4.5, or at least about 5 percent of the average residencetime of the articles passing through the initial thermal regulation zone16.

When the articles are being pasteurized, the average residence time ofthe articles passing through the RF heating zone 18 can be about 0.5percent to about 20 percent or about 2 percent to about 6 percent of theaverage residence time of the articles passing through the initialthermal regulation zone 16. Alternatively, when the articles are beingsterilized, the average residence time of the articles passing throughthe RF heating zone 18 can be about 1 percent to about 30 percent, orabout 4 percent to about 10 percent of the average residence time of thearticles passing through the initial thermal regulation zone 16.

Further, as also shown in FIG. 13, the average residence time of thearticles in the RF heating zone 18 is significantly shorter than theresidence time of the articles in any one portion of the subsequentthermal regulation zone 20, as well as the overall residence time of thearticles in the subsequent thermal regulation zone 20. For example, insome embodiments, the average residence time of the articles passingthrough the RF heating zone 18 can be at least about 0.25, at leastabout 0.50, at least about 1, at least about 1.5, or at least about 2percent and/or not more than about 20, not more than about 18, not morethan about 15, not more than about 12, not more than about 10, not morethan about 8, not more than about 6, not more than about 5, or not morethan about 4 percent of the average overall residence time of thearticles passing through the subsequent thermal regulation zone 20. Whenthe articles are being pasteurized, the average residence time of thearticles passing through the RF heating zone 18 can be about 0.25percent to about 15 percent, or about 1 percent to about 4 percent ofthe overall average residence time of the articles passing throughsubsequent thermal regulation zone 20. When the articles are beingsterilized, the average residence time of the articles passing throughthe RF heating zone 18 can be about 1 percent to about 20 percent, orabout 2 percent to about 6 percent of the average residence time of thearticles passing through the subsequent thermal regulation zone 20.

When the subsequent thermal regulation zone 20 includes a thermal holdzone 30 as shown in FIG. 3, the average residence time of the articlesin the thermal hold zone 30 can be longer than the average residencetime of the articles in the RF heating zone 18. For example, in certainembodiments, the average residence time of the articles in the RFheating zone 18 can be at least about 2, at least about 5, at leastabout 8, or at least about 10 percent and/or not more than about 50, notmore than about 45, not more than about 40, not more than about 35, notmore than about 30, or not more than about 25 percent of the averageresidence time of the articles in the thermal hold zone 30, which willbe discussed in further detail below. When a hold zone 30 is present,the average residence time of the articles in the RF heating zone 18 canbe in the range of from about 5 percent to about 50 percent, about 8percent to about 45 percent, or about 10 percent to about 40 percent ofthe average residence time of the articles in the hold zone 30.

Despite having the shortest residence time of all processing steps inliquid contact zone 14, the RF heating zone may be configured to heatthe articles passing therethrough in order to achieve the largest changein temperature, as compared to the other processing zones, asillustrated in FIG. 13. In some embodiments, the temperature at thegeometric center of the articles exiting the RF heating zone 18 can beat least about 60, at least about 65, at least about 70, at least about75, at least about 80, at least about 85, at least about 90, at leastabout 95, at least about 100, at least about 105, or at least about 110°C. and/or not more than about 135, not more than about 130, not morethan about 125, not more than about 120, not more than about 115, notmore than about 110, or not more than about 105° C. When beingpasteurized, the temperature at the geometric center of the articlesexiting the RF heating zone 18 can be in the range of from about 65° C.to about 115° C. or about 80° C. to about 105° C. When being sterilized,the temperature at the geometric center of articles exiting the RFheating zone 18 can be in the range of from about 95° C. to about 135°C., or about 110° C. to about 125° C.

In some cases, the average difference between the maximum temperature(hottest portion) and minimum temperature (coldest portion) within eachof the articles exiting the RF heating zone 18 is not more than about25, not more than about 20, not more than about 15, not more than about10, not more than about 5, or not more than about 2° C. The averagedifference between the temperatures at the geometric centers of adjacentarticles exiting the RF heating zone 18 can be not more than about 20,not more than about 15, not more than about 10, not more than about 5,not more than about 2, or not more than about 1° C. In certainembodiments, the articles withdrawn from the RF heating zone 18 can beuniformly heated so that, for example, the temperature of at least about95, at least about 98, or at least about 99 percent of the total volumeof the articles can be within an about 25, about 20, about 15, about 10,about 5, about 2.5, or about 2° C. temperature range.

Achievement of desirable temperatures in the RF heating zone 18 may bedue, at least in part, to the configuration of the RF heating zone 18.In certain embodiments, the RF heating zone 18 can be configured tomaximize the intensity and efficiency of the heating performed therein.For example, in certain embodiments, the RF heating zone 18 may beconfigured to maximize energy absorption by the foodstuff or otheredible substance to achieve the desired level of sterilization orpasteurization while also minimizing thermal degradation. In certainembodiments, the articles heated in the RF heating zone 18 may absorb RFenergy at an average lengthwise energy absorption rate of at least 2×10⁵Joules per foot (J/ft). The average lengthwise energy absorption rate(R_(A)) for a given article is determined by the following formula:

${R_{A} = \frac{\left( {{c_{p}{mT}_{f}} - T_{i}} \right)}{L_{c}}},$

where c_(p) is the specific heat of the foodstuff or other substancecontained in the package, m is the mass of the foodstuff, T_(f) andT_(i) are the final and initial temperatures of the foodstuff (or otheredible substance) measured at its geometric center, and L_(c) is thelength of the RF heating zone 18. In some embodiments, the averagelengthwise energy absorption rate for articles passing through the RFheating zone 18 can be at least about 1×10⁴, at least about 2×10⁴, atleast about 5×10⁴, at least about 8×10⁴, at least about 1×10⁵, at leastabout 2×10⁵, at least about at least about 5×10⁵, or at least about atleast about 1×10⁶ J/ft and/or not more than about 5×10⁶, not more thanabout 2×10⁶, not more than about 1×10⁶, not more than about 8×10⁵, notmore than about 5×10⁵, or not more than about 3×10⁵ J/ft, or it can bein the range of from about 1×10⁴ J/ft to about 1×10⁶ J/ft or in therange of from about 1×10⁵ J/ft to about 3×10⁵ J/ft.

Additionally, in certain embodiments, the articles heated in RF heatingzone 18 may have an average lengthwise center point heating rate of atleast about 2° C./foot (° C./ft) and not more than about 100° C. perfoot (° C./ft), measured at the geometric center of the article. Thelengthwise center point heating rate (R_(cp)) is calculated according tothe following formula:

${R_{cp} = \frac{\left( {T_{cpf} - T_{cpi}} \right)}{L_{c}}},$

where T_(cpf) is the final temperature of the geometric center of thearticle at the outlet of the RF heating zone 18, T_(cpi) is the initialtemperature of the geometric center of the article at the inlet of theRF heating zone 18, and L_(c) is the length of the RF heating zone 18.In some embodiments, the average lengthwise center point heating rate ofarticles heated in the RF heating zone 18 can be at least about 2, atleast about 3, at least about 5, at least about 8, or at least about 10°C./ft and/or not more than about 100, not more than about 90, not morethan about 80, not more than about 70, not more than about 60, not morethan about 50, not more than about 40, or not more than about 30° C./ft,or it can be in the range of from about 2° C./ft to about 100° C./ft orabout 10° C./ft to about 30° C./ft.

In certain embodiments, the articles heated in the RF heating zone 18may be exposed to RF energy at an average lengthwise power intensity ofat least about 3 kW per foot (kW/ft). The average lengthwise powerintensity (R_(I)) for a given article is determined by the followingformula:

${R_{I} = \frac{P_{C}}{L_{c}}},$

where P_(C) is the total cumulative power (in kW) to which the articleshave been exposed in the RF heating zone, and L_(c) is the length of theRF heating zone 18 (in feet). In some embodiments, the averagelengthwise power intensity for articles passing through the RF heatingzone 18 can be at least about 1, at least about 1.5, at least about 2,at least about 3, at least about 4, at least about 5, at least about 8,or at least about 10 kW per foot (kW/ft) and/or not more than about 30,not more than about 25, not more than about 20, not more than about 15,not more than about 10, not more than about 8, or not more than about 5kW/ft.

Turning now to FIGS. 14 through 18, several views of the RF heatingsection of the heating system of the present invention are shown. The RFheating section may include an RF generator 328, an RF energytransmission system 330, and an RF applicator 332, which can define theRF heating zone 318. RF energy from the RF generator 328 may be passedby the RF energy transmission system 330 to the RF applicator 332 anddischarged into the RF heating zone 318, which is generally definedwithin the RF applicator 332. Once in the RF heating zone 318, the RFenergy may be used to heat articles 100 passing therethrough along atleast one convey line 370. In some embodiments, the RF heating sectionmay further include a pressure vessel 350, in which the RF applicator332 and the RF heating zone 318 may be disposed.

The RF generator 328 may be any device suitable for producing RF energy.In certain embodiments, the RF generator 328 can generate power in anamount of at least about 10, at least about 20, at least about 25, atleast about 30, at least about 35 kW and/or not more than about 500, notmore than about 250, not more than about 200, not more than about 150,not more than about 100, or not more than about 50 kW. RF heatingsystems of the present invention may use a single RF generator, or twoor more RF generators to provide sufficient energy to the RF heatingzone 318.

The RF applicator 332 defines RF heating zone 318 and can be configuredto act as a resonant cavity for the RF energy. In certain embodiments,the RF applicator 332 may be a split applicator having an upperapplicator section 360, a lower applicator section 362 spaced apart fromthe upper applicator section 360, and at least one opening 356 definedbetween the upper section 360 and the lower section 362. Embodiments ofsplit RF applicators 332 are shown in FIGS. 17 and 18. In someembodiments, as shown in FIG. 17, the split RF applicator 332 mayinclude a single opening 356, while, in other embodiments, as shown inFIG. 18, the split RF applicator 332 may include two openings 356 a,b.When the RF applicator 332 includes at least one opening 356, at leastone RF choke 364 may be located proximate to the opening 356 to inhibit,or prevent, RF energy from passing out of the opening 356. As shown inFIG. 18, when the split RF applicator 332 has two openings 356 a,b, eachopening 356 a,b may include a choke 364 a,b proximate to it forinhibiting or preventing RF energy from passing out of each respectiveopening 356 a,b.

The RF energy transmission system 330 is configured to transport RFenergy from the RF generator 328 and into the RF applicator 332 therebycreating the RF heating zone 18 in the RF applicator 332. Severalcomponents of an RF energy transmission system 330 configured accordingto embodiments of the present invention are shown in FIGS. 14-18. Forexample, as shown in FIGS. 15 and 16, the RF energy transmission system330 may include at least one coaxial conductor 334, at least onewaveguide 336, and at least one coax-to-waveguide transition 338. RFenergy produced by the RF generator 328 may be transferred by thecoaxial conductor 334 and into the waveguides 336, which are locatedoutside the RF heating zone 18. The coax-to-waveguide transition 338 maybe configured to transition the RF energy from the coaxial conductor 334into the waveguide 336, which guides the RF energy into the RFapplicator 332.

In certain embodiments, the waveguide 336 may be at least partiallyfilled with a liquid medium, such as, for example, water. When thewaveguide 336 is at least partially filled with a liquid medium, thedimensions of the waveguide may be much smaller than if the waveguidewere filled with air. For example, in certain embodiments, the waveguide336 can have a generally rectangular cross-section with the dimension ofthe widest waveguide wall being in the range of from about 5 inches toabout 40 inches or about 12 inches to about 20 inches, and the dimensionof the narrowest waveguide wall being in the range of from about 2inches to about 20 inches, about 4 inches to about 12 inches, or about 6inches to about 10 inches.

In addition, as shown in FIGS. 14 through 18, the RF energy transmissionsystem 330 may include at least one RF launcher 340 located between thewaveguide 336 and the RF applicator 332 for emitting RF energy into theRF applicator 332 and the RF heating zone 318. Each RF launcher 340 isconfigured to discharge energy from the waveguide 336 into the RFapplicator 332 and may include, for example, a narrow end 341 and abroad end 343. As shown in FIGS. 14 and 16, the narrow end 341 can becoupled to the waveguide 336, while the broad end 343 can be coupled tothe RF applicator 332. Although shown in FIGS. 14 through 18 asincluding an upper launcher 340 a and a lower RF launcher 340 b disposedon generally opposite sides of the pressure vessel 350, it should beunderstood that other configurations would also be suitable. Forexample, in some embodiments, the RF energy transmission system mayinclude a single RF launcher, while, in other embodiments, it mayinclude two or more RF launchers located on the same side of the vessel350 and spaced apart from one another along the direction of extensionof the vessel.

In certain embodiments, the interior of the upper RF launcher 340 aand/or lower RF launcher 340 b can be substantially empty. That is,there may be few or no additional structures located within the interiorof the upper RF launcher 340 a and/or the lower RF launcher 340 b. Suchstructures which may be absent from the interior of the upper RFlauncher 340 a and/or the lower RF launcher 340 b include, for example,dividing septa and irises.

As shown in FIGS. 14 through 18, in some embodiments, at least onewaveguide 336 may penetrate a wall 352 of the pressure vessel 350 sothat the RF applicator 332 can be disposed within the interior of thevessel 350. In some embodiments, the RF applicator 332 may be spacedinwardly from the wall 352 of the vessel 350, as shown in FIGS. 14through 18, while, in other embodiments, the RF applicator 332 may bepositioned proximate to or integrated with the wall 352. The RF energytransmission system 330 may include a pair of waveguides, shown as upperwaveguide 336 a and lower waveguide 336 b, that penetrate the sides ofthe vessel 350 at respective upper and lower locations. Each of theupper waveguide 336 a and lower waveguide 336 b may be configured toprovide RF energy to substantially opposite sides of the RF applicator332. In some embodiments as shown in FIGS. 14 to 18, all or a portion ofthe RF launchers 340 may also be present within the interior of thepressure vessel 350.

When the RF energy transmission system 330 includes an upper waveguide336 a and a lower waveguide 336 b, it may also include an upper coaxialconductor 334 a and a lower coaxial conductor 334 b, and an uppercoax-to-waveguide transition 338 a for coupling the upper coaxialconductor 334 a to the upper waveguide 336 a and a lowercoax-to-waveguide transition 338 b for coupling the lower coaxialconductor 334 b to the lower waveguide 336 b. One such embodiment isgenerally depicted in FIGS. 15 and 16.

The upper and lower coaxial conductors 334 a and 334 b may include aninner conductor and an outer conductor that extend coaxially from the RFenergy generator 328 to the inlet of the upper and lower waveguides 336a and 336 b respectively. As shown in FIG. 16, the outer conductor ofeach of the upper coaxial conductor 334 a and the lower coaxialconductor 334 b may terminate at the wall of respective upper and lowerwaveguides 336 a and 336 b. The inner conductor, however, may extendthrough one wall of each of the upper and lower waveguides 336 a and 336b and into the interior of the waveguides 336 a and 336 b, therebyforming respective upper and lower coax-to-waveguide transitions 338 aand 338 b. Optionally, the inner conductor of the upper or lowercoax-to-waveguide transitions 338 a and 338 b may extend through theopposite wall of the upper or lower waveguide 336 a or 336 b. Adielectric sleeve may surround the inner conductor where the innerconductor penetrates the wall or walls of the upper or lower waveguides336 a,b in order to prevent fluid from flowing into respective upper orlower coaxial conductor 334 a,b. The dielectric sleeve may be formedfrom any material capable of being sealed with the waveguide and that issubstantially transparent to RF energy. One example of a suitablematerial includes, but is not limited to, glass fiber filledpolytetrafluoroethylene (PTFE).

In certain embodiments, the RF applicator 332, within which the RFheating zone 318 is defined, can be in open communication with theinterior of the pressure vessel 350 and/or with the interior of at leastone waveguide 336. As used herein, the term “open communication” meansthat a fluid present in one of the RF applicator 332 and the interior ofthe pressure vessel 350 and/or the interior of the waveguide 336 may bepermitted to flow therebetween with little or no restriction. Such opencommunication may be facilitated by, for example, use of a split RFapplicator 332 that includes at least one opening 356 as discussedpreviously. With the use of one or more chokes at the opening of the RFapplicator 332, open fluid communication between the inside and theoutside of the RF applicator 332 can be maintained, while substantiallyall of the RF energy remains contained within the RF applicator 332.

When the RF applicator 332 is in open communication with the interior ofthe pressure vessel 350 and/or the interior of the waveguide 336 (orupper and lower waveguides 336 a,b, when present), each can have asimilar pressure. In some embodiments, the pressure within the RFapplicator 332 and the interior of the pressure vessel 350 and/or thewaveguide 336 can be at least about 5, at least about 10, at least about15, at least about 20, or at least about 25 psig and/or not more thanabout 80, not more than about 70, not more than about 60, not more thanabout 50, not more than about 40, or not more than about 35 psig. Whenthe articles 100 are being pasteurized, the pressure can be in the rangeof from about 1 psig to about 40 psig or about 2 psig to about 20 psig.When the articles 100 are being sterilized, the pressure can be in therange of from about 5 psig to about 80 psig, or about 15 psig to about40 psig. The RF heating zone 318 and articles 100 passing therethroughmay also be at or near a pressure within one or more of the aboveranges.

In certain embodiments, the interior of the RF applicator 332, theinterior of the pressure vessel 350, and, optionally, the upperwaveguide 336 a and lower waveguide 336 b may be filled with a commonliquid. The liquid can act as a transfer medium through which RF energyis passed as it is directed toward to the articles 100 passing throughRF heating zone 318. The RF heating zone 318 may also be filled with theliquid medium and the articles 100 being heated may be submerged in theliquid while passing through the RF heating zone 318. The liquid mediumcan comprise, or be, any of the aforementioned types of liquid and, insome embodiments, may be pretreated in order to minimize itsconductivity. For example, in some embodiments, the liquid may betreated so that it has a dielectric constant of not more than about 100,not more than about 90, not more than about 80, not more than about 70,not more than about 60, not more than about 50, not more than about 40,not more than about 30, not more than about 20, not more than about 10,not more than about 5, not more than about 1, or not more than about 0.5mS/m. In some embodiments, the liquid can comprise or be deionized ordistilled water.

As the articles 100 pass through RF heating zone 318, at least a portionof the RF energy discharged therein may be used to heat the articles100. The RF heating portion of the RF heating system may include atleast one convey line for transporting the articles 100 through the RFheating zone and into and out of the pressure vessel. Any suitable typeof conveyor can be used to form the convey line, including, for example,plastic or rubber belt conveyors, chain conveyors, roller conveyors,flexible or multi-flexing conveyors, wire mesh conveyors, bucketconveyors, pneumatic conveyors, trough conveyors, vibrating conveyors,and combinations thereof.

In some embodiments, the convey line may include a single convey segmentwhile, in other embodiments, the convey line may include two or moreconvey segments arranged in parallel or series. One example of a conveyline 370 suitable for use in the RF heating section of the presentinvention is shown in FIG. 19. As shown in FIG. 19, the convey line 370is disposed in the pressure vessel 350 and is configured to transportarticles 100 in the direction of extension of the central axis of thepressure vessel 351. In the embodiment shown in FIG. 19, the convey line370 includes an approach conveyor 410, a take-away conveyor 420, and anRF zone conveyor 430. The approach conveyor 410 may be configured totransport the articles 100 through an entrance opening 406 in thepressure vessel 350 toward the RF heating zone 318 defined within RFapplicator 332, and the take-away conveyor 420 may be configured totransport the articles 100 through an exit opening 408 away from the RFheating zone 318. The RF zone conveyor 430 can transport the articles100 through the RF heating zone 318 while the articles are being heatedwith RF energy. The articles 100 are loaded onto the RF zone conveyor430 in a loading zone 412 and unloaded from the RF zone conveyor 430 inan unloading zone 414.

The approach conveyor 410, take-away conveyor 420, and RF zone conveyor430 may be operated so that the average velocity of the articles 100passing through RF heating zone 318 may be at least about 0.05, at leastabout 0.10, at least about 0.15, or at least about 0.20 inches persecond (in/s) and/or not more than about 10, not more than about 8, notmore than about 6, not more than about 5, not more than about 4, notmore than about 3, not more than about 2, or not more than about 1 in/s,or it can be in the range of from about 0.10 in/s to about 10 in/s,about 0.15 in/s to about 5 in/s, or about 0.2 to about 2 in/s. In someembodiments, the articles may pass through the RF heating zone at a rateof at least about 5, at least about 10, at least about 15, at leastabout 20, or at least about 25 articles per minute and/or not more thanabout 100, not more than about 75, not more than about 50, not more thanabout 30, or not more than about 25 articles per minute.

Each of the approach conveyor 410, the take-away conveyor 420, and theRF zone conveyor 430 may be operated at similar speeds or one or moremay be operated at different speeds. For example, in some embodiments,the approach conveyor 410 and the take-away conveyor 420 may be operatedat velocities that are at least 1.25, at least about 1.5, at least about1.75, at least about 2, at least about 2.5, or at least about 3 timesfaster than the velocity of the RF zone conveyor 430. As such, theaverage centerpoint-to-centerpoint spacing of the articles 100 on theapproach conveyor 410 and/or the take-away conveyor 420 can be at leastabout 1.25, at least about 1.5, at least about 1.75, or at least about 2times greater than the spacing of articles 100 on the RF zone conveyor430.

Such differences may depend, at least in part, on the particularconfiguration of each conveyor and can be used to ensure a consistentmass convey rate of the articles 100 through the pressure vessel. Incertain embodiments, the total mass convey rate of the articles 100passing through the RF heating zone 318 can be at least about 5, atleast about 10, at least about 15, at least about 25, at least about 30,at least about 35, at least about 40, at least about 45, at least about50, at least about 55, at least about 60, at least about 65, at leastabout 70, or at least about 75 pounds per minute (lb/min) and/or notmore than about 1000, not more than about 900, not more than about 800,not more than about 700, not more than about 600, not more than about500, not more than about 400, not more than about 300, not more thanabout 200, or not more than about 100 lb/min, or it can be in the rangeof from about 5 to about 1000 lb/min or about 75 to about 200 lb/min.

Turning now to FIGS. 20 through 23, several aspects of an RF heatingsection that includes an RF zone conveyor configured according tocertain embodiments of the present invention are illustrated. The RFzone conveyor shown in FIGS. 20 through 23 is a swing arm conveyor thatincludes a plurality of spaced-apart article supporting members 434 forengaging, supporting, and moving the articles 100 through the RF heatingzone 318. The article supporting members 434 are coupled to a drivemechanism 426 that moves the article supporting members 434 from theloading zone 412, through the RF heating zone 318, and to an unloadingzone 414. The articles 100 passing through RF heating zone 318 may beheld in article-receiving spaces 436 that are defined between adjacentarticle-supporting members 434, as generally shown in FIGS. 21 and 22.

The drive mechanism 426 of the swing arm conveyor may be any device orsystem suitable for moving the article supporting members 434 throughthe RF heating zone 318. In some embodiments, the drive mechanism 426may be a continuous drive mechanism. In certain embodiments, asparticularly illustrated in FIG. 20, the drive mechanism 426 can includea belt or chain 425, a pulley or sprocket 427, and a motor 429 forrotating the sprocket or pulley 427 with the belt or chain 425.Additionally, the belt or chain 425 can include a plurality of anchors431 to which individual article-supporting members 434 may be coupled.All, or a portion, of the drive mechanism 426 may be located outside theRF heating zone 318, but within the interior of the pressure vessel 350,as shown in FIGS. 20 and 21. When the pressure vessel 350 is filled witha liquid medium, the drive mechanism 426 may be configured to be atleast partially, or completely, submerged in the liquid medium duringoperation.

Turning now to FIGS. 24 through 27, several views of an articlesupporting member 434 suitable for use with a swing arm conveyoraccording to various embodiments of the present invention are shown. Thearticle supporting member 434 has a free end 438, a connected end 440,and a longitudinal axis 435 extending from the connected end 440 to thefree end 438. As shown in FIG. 24, the connected end 440 is configuredto be coupled to a belt or chain 425, which is part of the drivemechanism 426 of the swing arm conveyor. In some embodiments, theconnected end 440 may be rigidly connected to the belt or chain 425 ofdrive mechanism 426, so that the article supporting member 434 remainsin generally the same position as it moves along the entire travel pathwithin the pressure vessel.

In other embodiments, the connected end 440 may be rotatably coupled tothe drive mechanism 426 so that, for example, the article supportingmember 434 may pivot or otherwise rotate during at least a portion ofits movement through the pressure vessel 350. One example of an articlesupporting member 434 having a connected end 440 capable of beingrotatably coupled to the drive mechanism 426 is shown in FIG. 25. Asshown in FIG. 25, the connected end 440 of the article supporting member434 presents a slot 441 into which an anchor 431 of the continuous drivemechanism 426 may be inserted. When the anchor 431 is inserted into theslot 441, the holes in the anchor 431 and the connected end 440 align,and a pin 443 may be inserted into the holes. This not only secures thearticle supporting member 434 to the belt or chain 425, but also permitsthe article supporting member 434 to pivot vertically so that it can bein different positions as it moves along the travel path.

In some embodiments, the connected end 440 may include a releasableattachment mechanism for readily permitting removal and replacement ofthe article supporting member 434 from the drive mechanism 426. Forexample, as shown in FIG. 25, the pin 443 may be removable, so thatanother article supporting member having a different shape, butsimilarly configured connected end 440, may be secured to the belt orchain 425 as described previously. In other embodiments, the articlesupporting member may be fixed and not removable from the continuousdrive mechanism 426 without damaging the swing arm conveyor.

As shown in FIGS. 24 through 27, the article supporting member 434comprises an elongated convey arm 450 and an article contact member 452coupled to the elongated convey arm 450 and configured to contact and atleast partially surround the article as it is passed through the RFheating zone. The elongated convey arm 450 may be formed from agenerally rigid material and, in some embodiments, may not absorbenergy. For example, in certain embodiments, the elongated convey arm450 can have a dielectric loss factor of not more than about 10, notmore than about 8, not more than about 6, not more than about 4, notmore than about 2, or not more than about 1, measured as describedherein. Additionally, or in the alternative, the elongated convey arm450 may have a conductivity of at least about 1×10⁶, at least about2×10⁶, at least about 5×10⁶ Siemens per meter (S/m). The elongatedconvey arm 450 may be formed from, for example, stainless steel oranother metal.

The article contact member 452 of the article supporting member 434 mayinclude an energy-absorptive component 454. The energy-absorptivecomponent can be capable of absorbing energy and may, for example, havea dielectric constant of at least about 20, at least about 25, at leastabout 30, at least about 35, at least about 40, at least about 45, or atleast about 50 and/or not more than about 150, not more than about 140,not more than about 130, not more than about 120, not more than about110, not more than about 100, not more than about 90, not more thanabout 80, not more than about 70, or not more than about 60, or it canbe in the range of from about 20 to about 150, about 30 to about 100, orabout 40 to about 60. Alternatively, or in addition, theenergy-absorptive component 454 can have a dielectric loss factor of atleast about 10, at least about 20, at least about 30, at least about 40,at least about 50, at least about 100, at least about 150, or at leastabout 200 and/or not more than about 1500, not more than about 1250, notmore than about 1000, or not more than about 800, or it can be in therange of from about 10 to about 1500, about 50 to about 1500, about 100to about 1250, or about 200 to about 800.

In some embodiments, it may be possible to form the article contactmember 452 of the article supporting member 434 so that the dimensionsand/or dielectric properties of the article contact member 452 aresimilar to those of the package holding the ingestible substance and/orthe ingestible substance itself. For example, the article contact member452 (or the energy-absorptive component 454) may have a dielectricconstant within about 50, within about 45, within about 40, within about35, within about 30, within about 25, within about 20, within about 15,or within about 10 percent of the dielectric constant of the ingestiblesubstance. Alternatively, or in addition, the article contact member 452(or the energy-absorptive component 454) can have a dielectric lossfactor within about 50, within about 45, within about 40, within about35, within about 30, within about 25, within about 20, within about 15,or within about 10 percent of the dielectric loss factor of theingestible substance. In some embodiments, the dielectric constantand/or dielectric loss factor of the article contact member 452 can becontrolled during the formation of the energy-absorptive component 454.For example, changing the composition of the energy-absorptive component454 may change the dielectric properties of the article contact member452.

In some embodiments, the RF heating system may include two or more setsof article supporting members that each have different dimensionaland/or dielectric characteristics. This permits the swing arm conveyorto be operated in at least two different configurations, each oneemploying a plurality of article supporting members configured tocontact and support packaged articles having different dimensionaland/or dielectric characteristics. For example, one set of articlesupporting members may be configured to hold a different number ofpackages, or may be configured to hold larger or smaller packages, orpackages of a different shape than the other set. Additionally, or inthe alternative, the energy-absorptive material used to form the articlecontact members on one set of the article supporting members may have adifferent dielectric constant and/or dielectric loss than theenergy-absorptive material used with the other set. In such embodiments,each of the article supporting members 434 may include a releasableattachment so that the article supporting members of one set may beeasily replaced with the article supporting members of another set sothat the RF conveyor can be run in a different configuration. Oneexample of a releasable attachment is the anchor 431 and pin 443described previously with respect to FIG. 25. The swing arm conveyor caninclude any suitable number of sets of article supporting members, eachhaving dimensions and/or dielectric properties specifically configuredto process certain types of articles.

Turning again to FIGS. 24-27, the energy-absorptive component 454 ofeach article contact member 452 may be formed from an energy-absorptivematerial that may be shaped to permit the contact member 452 to supportand at least partially surround the article when the article supportingmember 434 moves the article through the RF heating zone. Theenergy-absorptive material may be a homogeneous (single) material, or itmay be a composite material formed from a mix or blend of two or moredifferent materials.

In certain embodiments, the energy-absorptive material can have adielectric constant of at least about 20, at least about 25, at leastabout 30, at least about 35, at least about 40, at least about 45, or atleast about 50 and/or not more than about 150, not more than about 140,not more than about 130, not more than about 120, not more than about110, not more than about 100, not more than about 90, not more thanabout 80, not more than about 70, or not more than about 60, or it canbe in the range of from about 20 to about 150, from about 30 to about100, or about 40 to about 60. Alternatively, or in addition, theenergy-absorptive material can have a dielectric loss factor of at leastabout 10, at least about 25, at least about 50, at least about 100, atleast about 150, or at least about 200 and/or not more than about 1500,not more than about 1250, not more than about 1000, or not more thanabout 800, or it can be in the range of from about 10 to about 1500,about 100 to about 1250, or about 200 to about 800.

In certain embodiments, the energy-absorptive material used to form theenergy-absorptive component 454 may be a homogeneous material. As usedherein, the term “homogeneous” refers to a single type of materialhaving an overall purity of at least about 98 weight percent, based onthe entire weight of the material or component. For example, in somecases, the homogeneous energy-absorptive material can include a singletype of material in an amount of at least about 98.5, at least about 99,at least about 99.5, or at least about 99.9 weight percent. Conversely,a homogenous energy-absorptive material may also include not more thanabout 2, not more than about 1.5, not more than about 1, not more thanabout 0.5, or not more than about 0.1 weight percent of components otherthan the single type of energy-absorptive material. When formed from ahomogenous material, the energy-absorptive component 454 can include oneor more layers of the material stacked upon one another, or it maycomprise a solid mass of the energy-absorptive material formed by, forexample, melting, blending, or binding powders, pellets, or particles ofthe energy-absorptive material.

In other embodiments, the energy-absorptive material may comprise acomposite material having two or more different types of materialblended, mixed, or otherwise combined with one another. The types andamounts of materials combined to form a composite energy-absorptivematerial may vary and may be selected in order to achieve one or moredesirable properties in the final energy-absorptive component 454. Forexample, in some embodiments, the composite material may comprise ablend of a polymeric material having a low dielectric loss and a solidelectrolyte material having a higher loss. The type and amount ofcomponents in the composite material may be selected so that at leastone of the dielectric loss, dielectric constant, and conductivity of theenergy absorptive material (or final energy-absorptive component 454) iswithin about 20, within about 15, within about 10, within about 5, orwithin about 2 percent of the dielectric loss, dielectric constant, orconductivity of the ingestible substance or article being heated.

Suitable composite energy-absorptive materials can have a dielectricconstant of at least about 20, at least about 25, at least about 30, atleast about 35, at least about 40, at least about 45, or at least about50 and/or not more than about 150, not more than about 140, not morethan about 130, not more than about 120, not more than about 110, notmore than about 100, not more than about 90, not more than about 80, notmore than about 70, or not more than about 60, or it can be in the rangeof from about 20 to about 150, from about 30 to about 100, or about 40to about 60. Alternatively, or in addition, composite material, whenused, can have a dielectric loss factor of at least about 10, at leastabout 25, at least about 50, at least about 100, at least about 150, orat least about 200 and/or not more than about 1500, not more than about1250, not more than about 1000, or not more than about 800, or it can bein the range of from about 10 to about 1500, about 100 to about 1250, orabout 200 to about 800.

The energy-absorptive material may also have a conductivity in the rangeof from about 0.01 to about 10 Siemens per meter (S/m), or at leastabout 0.01, at least about 0.05, at least about 0.075, at least about0.1, at least about 0.25, at least about 0.3, at least about 0.5, atleast about 1, at least about 1.5, at least about 2, at least about 2.5,at least about 3, at least about 3.5, at least about 4, at least about4.5, or at least about 5 S/m and/or not more than about 10, not morethan about 9.5, not more than about 9, not more than about 8.5, not morethan about 8, not more than about 7.5, or not more than about 7 S/m, orit can be in the range of from about 0.2 to about 9 S/m, at least about0.25 to about 8.5 S/m, or at least about 0.3 to about 8 S/m.Additionally, the solid electrolyte material, when present, may alsohave a conductivity within one or more of the above ranges, and may havea conductivity the same as or different than the energy-absorptivematerial.

In some embodiments, the energy-absorptive material may comprise atleast one solid electrolyte material. Examples of suitable solidelectrolyte materials can include, but are not limited to, polymersincluding repeat units of perfluorosulfonic acid. In some embodiments,the solid electrolyte material can comprise copolymers ofperfluorosulfonic acid and polytetrafluoroethylene (PFSA-PTFE), whichmay be chemically stabilized and/or in the acid form. One example ofsuch a polymer is Nafion® PFSA commercially available from DuPont™.

When used as the energy-absorptive material, the solid electrolyte canhave a dielectric constant and/or dielectric loss factor within one ormore of the above ranges. When used to form the energy-absorptivecomponent 454, the solid electrolyte material may be in any suitableform. In some cases, solid electrolyte materials may be used as ahomogeneous energy-absorptive materials, while in others solidelectrolytes may be part of a composite energy-absorptive material. Forexample, in some embodiments, the solid electrolyte material may be inthe form of a film or membrane and may be stacked in layers to form theenergy-absorptive component. When all of the layers are formed from thesame solid electrolyte material, the resulting energy-absorptivematerial may be homogeneous, while alternating one or more layers with adifferent material may form a composite energy-absorptive material. Instill other embodiments, the energy-absorptive component may be formedfrom a powder, pellets, or particles of solid electrolyte material,which may be blended, mixed, melted, or otherwise combined with one ormore other components to form a composite solid electrolyte material.Examples of suitable components that may be combined with the solidelectrolyte material include, but are not limited to, binders, polymers,rubbers, other solid electrolyte materials, and combinations thereof.

In certain embodiments, the energy-absorptive material may be acomposite material comprising a polymeric binder and a plurality ofsolid particles dispersed in the polymeric binder. Such materials canhave a dielectric constant and/or dielectric loss factor similar to, orthe same as, the energy-absorptive component 454, while, in otherembodiments, the dielectric constant and/or dielectric loss factor ofthe composite polymeric material may be less than the dielectricconstant and/or dielectric loss factor of the energy-absorptivecomponent 454.

When the energy-absorptive material is a composite material including apolymeric binder and a plurality of solid particles dispersed in thepolymeric binder, the polymeric binder may be present in the compositematerial in an amount in the range of from about 10 to about 99.5 weightpercent, based on the total weight of the composite material. In someembodiments, the polymeric binder may be present in an amount of atleast about 10, at least about 20, at least about 25, at least about 30,at least about 35, at least about 40, at least about 45, at least about50, at least about 55, at least about 60, at least about 65, at leastabout 70 weight percent and/or not more than about 99.5, not more thanabout 99, not more than about 97, not more than about 95, not more thanabout 90, not more than about 85, not more than about 80, not more thanabout 75, not more than about 70, not more than about 65, not more thanabout 60, or not more than about 55 weight percent, based on the totalweight of the composite material. The polymeric binder may be present inthe composite material in an amount in the range of from about 10 weightpercent to about 99.5 weight percent, about 20 weight percent to about90 weight percent, or about 40 weight percent to about 60 weightpercent.

The polymeric binder can include any moldable polymeric materialsuitable for use in an RF heating zone. In certain embodiments, thepolymeric binder can have a dielectric constant and/or dielectric lossfactor of not more than about 10, not more than about 8, not more thanabout 6, not more than about 4, not more than about 2, or not more thanabout 1. In certain embodiments, the polymeric binder may compriserubber. Examples of suitable rubbers include, but are not limited to,chloroprene (neoprene), ethylene-propylene-diene (EDPM),ethylene-propylene, nitrile-butadiene, polysiloxane (silicone),styrene-butadiene, isobutene-isoprene (butyl), isoprene, natural rubber,chloro-sulfonyl-polyethylene, polyethylene-adipate,poly(oxy-1,4-butylene)ether (urethane), hexafluoropropylene-vinylidenefluoride, fluorocarbon, hydrogenated acrylonitrile-butadiene,carboxylated nitrile, and combinations thereof. In certain embodiments,the rubber may be silicone rubber.

When used, the solid particles dispersed in the polymeric binder of thecomposite material may be present in an amount of at least about 0.5, atleast about 1, at least about 5, at least about 10, or at least about 15weight percent and/or not more than about 50, not more than about 45,not more than about 40, not more than about 35, or not more than about30 weight percent, based on the total weight of the composite material.In certain embodiments, the solid particles may be present in an amountin the range of from about 0.5 weight percent to about 50 weightpercent, about 1 weight percent to about 40 weight percent, or about 2weight percent to about 20 weight percent, based on the total weight ofthe composite material. The weight ratio of solid particles to polymericbinder in the composite material can be at least about 1:100, at leastabout 1:75, or at least about 1:50 and/or not more than about 1:1, notmore than about 1:1.5, or not more than about 1:2, or it can be in therange of from about 1:100 to about 1:1, about 1:75 to about 1:1.5, orabout 1:50 to about 1:2.

The solid particles dispersed in the polymeric binder of the compositematerial can be any solid particles that increase the dielectricconstant and/or dielectric loss factor of the polymeric binder so that,for example, the dielectric constant and/or dielectric loss factor ofthe composite material is higher than it would be if the compositematerial were formed only from the polymeric binder. The solid particlesmay have an average particle size of at least about 5, at least about10, at least about 15, at least about 20, at least about 25, at leastabout 30, at least about 35, at least about 40, at least about 45, or atleast about 50 nanometers (nm) and/or not more than about 1000, not morethan about 900, not more than about 800, not more than about 700, notmore than about 600, not more than about 500, not more than about 400,not more than about 300, not more than about 200, or not more than about100 nm, or it can be in the range of from about 5 nm to about 1000 nm,about 20 nm to about 500 nm, about 10 nm to about 250 nm, or about 50 toabout 100 nm. In some embodiments, the solid particles may comprise acarbon black. In other embodiments, the solid particles may comprisesolid electrolyte materials. The selection of the specific type and/oramount of solid particles in the polymeric binder in the compositematerial used to form the energy-absorptive component 454 (or articlecontact member 452) may help control the final dielectric properties ofthe article contact member 452.

In certain embodiments, the energy-absorptive component 454 may furtherinclude a plurality of spaced-apart conductive elements 456, as shown inFIG. 25. Use of the conductive elements 456, which can include, forexample, metallic plates, may permit adjustment of the dielectricconstant and/or dielectric loss factor of the energy control component454. For example, in some embodiments, the energy-absorptive materialmay have a dielectric constant and/or dielectric loss factor less thanthe dielectric constant and/or dielectric loss factor of theenergy-absorptive component 454, when the conductive elements 456 arepresent. When present, the conductive elements 456 may be configured sothat the energy-absorptive material can be received between theconductive elements 456 to form the energy-absorptive component 454.Conductive elements 456 may be formed from a conductive material and canhave a conductivity of at least about 1×10⁶, at least about 2×10⁶, atleast about 5×10⁶ Siemens per meter (S/m) and may comprise, for example,a plurality of metallic plates. Stainless steel is one example of asuitable metal for use in forming one or more of the conductive elements456. In some embodiments, the energy-absorptive component 454 does notinclude any conductive elements.

Additionally, as shown particularly in FIGS. 26 and 27, the articlecontact member 452 can include an insulating component 458. Theinsulating component 458 of the article contact member 452 can beconfigured to contact and support one of the articles 100 when thearticle supporting member 434 is transporting the article through the RFheating zone. The insulating component 458 may cover all or a portion ofthe outer surface of the energy-absorptive component 454, and may bepositioned between the energy-absorptive component 454 and the packageof the article when the article supporting member 434 is in contact withthe article to prevent the overheating of the article that may occur ifthe package were in direct contact with the energy-absorptive component454. The insulating component 458 may be present on at least about 50,at least about 55, at least about 60, at least about 65, at least about70, at least about 75, at least about 80, at least about 85, at leastabout 90, at least about 95, or all of the surface area of theenergy-absorptive component 454.

The insulating component 458 may be formed of an energy insulatingmaterial having a dielectric constant and/or dielectric loss factor ofnot more than about 10, not more than about 8, not more than about 6,not more than about 4, not more than about 2, or not more than about 1.In some embodiments, as generally illustrated in FIG. 26, the insulatingcomponent 458 may comprise a layer of the insulating material thatcovers at least a portion of the energy-absorptive component 454. Inother embodiments, as generally illustrated in FIG. 27, the insulatingcomponent may include a plurality of protrusions formed from theinsulating material and protruding from various portions of the surfaceof the energy-absorptive component 454. The insulating element 458 maybe present on at least 1, at least 2, at least 3, or 4 or more sides ofthe energy-absorptive component 454.

Turning again to FIGS. 20 through 24, the drive mechanism 426 of theswing arm conveyor may be configured to transport a plurality of articlesupport members 434 along a continuous travel path throughout theinterior of vessel 350. As shown in FIGS. 22 and 23, the continuoustravel path may include a heating path 443 for transporting articles 100through the RF heating zone, a return path 445 for transporting thearticle supporting members 434 from the unloading zone 414 to theloading zone 412, and two transition paths 447 a and 447 b fortransitioning the article supporting members between the heating path443 and the return path 445.

When the article supporting members 434 are passed along at least aportion of the heating path 443, the article supporting members 434 canbe configured in a heating orientation as shown in FIGS. 21 and 22.Article supporting members 434 a through 434 c shown in FIG. 23 are alsoconfigured in a heating orientation. When configured in the heatingorientation, the article supporting member may be oriented substantiallyhorizontally so that, for example, the longitudinal axis 435 of thearticle supporting member 434 is within about 30° of the horizontal. Incertain embodiments, an article supporting member configured in aheating orientation may be oriented so that its longitudinal axis iswithin about 25, within about 20, within about 15, within about 10,within about 5, within about 3, within about 2, or within about 1° ofthe horizontal, or it may be horizontal.

In certain embodiments, when oriented in the heating orientation, thefree end 438 of each article supporting member 434 can supported on anarm support member 442. The arm support member 442 can be any devicesuitable for supporting the free end 438 of the article supportingmember 434 such as, for example, a rail or other surface. Asparticularly shown in FIG. 21, when the RF applicator 332 is a splitapplicator, the arm support member 442 may be located outside the RFheating zone 318 so that at least a portion of each of the articlesupporting members 434 (e.g., the free end 438) can pass through theopening 356 defined between the upper applicator section 360 and thelower applicator section 362 of the split RF applicator 332 as thearticle supporting member 434 moves through the RF heating zone 318.Additionally, as shown in FIG. 21, the continuous drive 426 may also bepositioned outside of the RF heating zone 318, so that a portion of theconnected end 440 of the article supporting member is positioned in ornear the other opening defined by the upper applicator section 360 andthe lower applicator section 362.

As the article supporting members 434 are moved along the heating path443, the article contact members 452 of the article supporting members434 may support and hold articles 100 being transported through the RFheating zone 318. As the article supporting members 434 pass through theRF heating zone 318, the article contact member 452 (orenergy-absorptive component 454) may also be heated with RF energy. Insome embodiments, the temperature of the surface of the article contactmember 452 (or the energy-absorptive component 454) may increase by atleast about 5, at least about 10, at least about 15, at least about 20,at least about 25, or at least about 30° C. as the article supportingmember 434 passes through the RF heating zone 318.

When an article supporting member 434 reaches the end of the heatingpath 443, the article held in the article-receiving space 436 can beunloaded onto the take-away conveyor 420, as generally shown in FIGS. 20and 22. When the article is unloaded from the swing arm conveyor, thearticle supporting member 434 in contact with the front of the articlecan be moved out of contact with the article as the article supportingmember transitions from a heating orientation to a return orientationalong transition path 447 a, as generally shown in FIG. 22. At thispoint, the article-receiving space 436 defined between the articlesupporting member 434 that had been in contact with the front of thearticle and the adjacent article supporting member 434 still in contactwith the back of the article is larger than it was while the articlesupporting members 434 were transporting the article through the RFheating zone 318. In some cases, the maximum distance between adjacentarticle supporting members 434 in the unloading zone 414 can be at leastabout 1.5, at least about 2, at least about 2.5, or at least about 3times larger than the maximum distance between adjacent articlesupporting members 434 in the RF heating zone.

Turning now to FIG. 28, a partial view of unloading zone 414 is shown.As shown in FIG. 28, the article 100 being unloaded may be transitionedonto the take-away conveyor 420, which includes a plurality of take-awaypushing members 462 for sliding the articles 100 along a take-away track464. As the back of the article is contacted with one of the take-awaypushing members 462, the article 100 can be moved along the take-awaytrack 464 and out of contact with the article supporting member 434 incontact with the back of the article 100. The article 100 may then bemoved by take-away conveyor 420 to the next processing zone (not shown).

After the article 100 is unloaded from the swing arm conveyor, thearticle supporting member 434 may move along a transition path 447 a asit moves from the heating orientation to the return orientation, asgenerally shown in FIG. 22. In certain embodiments, the movement of thearticle supporting member 434 along the transition path 447 a mayinclude pivoting the article supporting member 434 downwardly through anangle of at least 45, at least about 50, at least about 55, at leastabout 60, at least about 65, at least about 70, at least about 75, atleast about 80, at least about 85, or at least about 90° from theheating orientation to the return orientation. Such movement may beaccomplished by permitting the article supporting member to move alongan inclined surface, such as a ramp, or the article supporting member434 may simply be permitted to drop downwardly.

As the article supporting members 434 are passed along at least aportion of the return path 445, the article supporting members 434 canbe configured in a return orientation as shown in FIG. 23. Articlesupporting members 434 e and 434 f shown in FIG. 23 are also configuredin a return orientation. In certain embodiments, the article supportingmember 434 in a return orientation does not support an article, and maybe oriented substantially vertically so that, for example, itslongitudinal axis is oriented within about 30° of the vertical. Incertain embodiments, an article supporting member 434 in a returnorientation can be oriented so that its longitudinal axis is orientedwithin about 25, within about 20, within about 15, within about 10,within about 5, within about 3, within about 2, or within about 1° ofthe vertical, or it may be vertical. When oriented in a returnorientation the free ends 438 of the article supporting members 434 arenot supported on the arm support member 442. In other embodiments (notshown), the article supporting member in a return orientation may beoriented so that its longitudinal axis is within about 30° of thehorizontal.

In certain embodiments, passing the article supporting members 434 alongthe return path in a vertical return configuration may permit reductionin the overall size of the pressure vessel 350. For example, when thepressure vessel 350 includes a cylindrical sidewall 352, as shown inFIG. 21, the diameter of the cylindrical sidewall can be not more than2.5 times the length of one of the article supporting members 434. Incertain embodiments, the diameter of the cylindrical sidewall 352 can benot more than about 2.4, not more than about 2.3, not more than about2.2, not more than about 2.1, not more than about 2.0, not more thanabout 1.9, or not more than about 1.8 times the length of one of thearticle supporting members 434. Each article supporting member can havea total length of at least about 6, at least about 8, at least about 10,at least about 12, at least about 14, at least about 16, or at leastabout 18 inches and/or not more than about 60, not more than about 50,not more than about 40, not more than about 30, or not more than about24 inches.

When the pressurized vessel 350 is a liquid-filled vessel, the articlesupporting members 434 moving from the unloading zone 414 to the loadingzone 412 along the return path 445 pass through a liquid medium. Incertain embodiments, this may help facilitate heat transfer between thesurface of the article contact members 452 (or energy-absorptivecomponents 454) which was heated during passage through the RF heatingzone 318 in order to cool the surface by at least about 5, at leastabout 10, at least about 15, at least about 20, at least about 25, or atleast about 30° C. As a result, the temperature of the surface of thearticle contact member 452 (or energy-absorptive component 454) returnedto the loading zone 412 can be within about 10, within about 8, withinabout 5, within about 3, within about 2, within about 1° C. or the sametemperature as the surface of the article contact member 452 (orenergy-absorptive component 454) immediately prior contacting an article100 being loaded onto the RF conveyor for passage through the RF heatingzone 318 (e.g., the initial contact surface temperature).

In certain embodiments, the article contact member 452 may include aplurality of heat transfer channels 460 extending through the articlecontact member 452, as generally shown in FIGS. 25 and 26. As thearticle supporting member 434 passes along the return path 445 shown inFIG. 20 and through the liquid medium, the liquid medium may passthrough the heat transfer channels 460 to facilitate cooling of thearticle contact member 452. The temperature of the liquid medium throughwhich the article supporting members 434 pass along the return path 445can be at least about 1, at least about 2, at least about 5, at leastabout 10, or at least about 15° C. cooler than the temperature of thesurface of the article contact member 452 immediately after removing thearticle from contact with the article supporting member 434 in theunloading zone 414 (e.g., the final contact surface temperature).

As shown in FIGS. 20 through 22, at any given time during the operationof swing arm conveyor, a portion of the article supporting members 434may be configured in the heating orientation and another portion of thearticle supporting members 434 may be configured in the returnorientation. As particularly shown in FIG. 23, article supportingmembers oriented in a return configuration (e.g., article supportingmembers 434 e and 434 f) may be configured so that the direction ofextension of the longitudinal axes of these support members is skewedrelative to the direction of extension of the longitudinal axes of thearticle supporting members that are oriented in a heating configuration(e.g., article supporting members 434 a-c). For example, in certainembodiments, the direction of extension of the longitudinal axis of anarticle supporting member in a return configuration can be skewed by atleast about 45, at least about 50, at least about 55, at least about 60,at least about 65, at least about 70, at least about 75, at least about80, at least about 85, or at least about 90° from the direction ofextension of the longitudinal axis of a corresponding article supportingmember in a heating configuration.

When the article supporting member 434 reaches the end of the returnpath 445, it may be moved along a second transition path 447 b as itmoves from the return orientation to the heating orientation. In certainembodiments, the article supporting member 434 may be pivoted upwardlythrough an angle until it reaches the heating orientation. In somecases, it may pivot upwardly through an angle of at least about 45, atleast about 50, at least about 55, at least about 60, at least about 65,at least about 70, at least about 75, at least about 80, at least about85, or at least about 90° when moving from the return orientation to theheating orientation. Such movement of the article supporting members 434may be achieved by, for example, permitting the article supportingmember 434 to move along an inclined surface such as a ramp 457 shown inFIG. 22.

When the article supporting members 434 return to the loading zone 412,articles 100 may be loaded into the receiving spaces between adjacentmembers. For example, as shown in FIG. 29, an article 100 may be loadedonto the RF zone swing conveyor by using an approach conveyor 410 topush the front of the article 100 into contact with a first articlesupporting member 434. The approach conveyor 410 may include a pluralityof approach pushing members 416 configured to contact the article 100and move it along an approach track 418 and into contact with an articlesupporting member 434. Next, an adjacent article supporting member (notshown in FIG. 29), which may be transitioning from the returnorientation to the heating orientation, may move into contact with theback of the article 100 as the article supporting member 434 enters theheating orientation, thereby securing the article 100 into the articleinto the article receiving space 436 between the adjacent articlesupporting members 434. As shown in FIG. 22, the adjacent articlesupporting member 434 moves into the loading zone 412, thearticle-receiving space 436 defined between the article supportingmember 434 contacting the front of the article 100 and the adjacentarticle supporting member 434 transitioning from the return orientationto the heating orientation in the loading zone 412 is larger than itwhen the article supporting members 434 are in contact with the article100 and moving it through the RF heating zone 318.

Returning again to FIG. 1, the articles exiting the RF heating zone 18may be introduced into a subsequent thermal regulation zone 20, wherein,ultimately, the average temperature at the geometric center of thearticles can be reduced by at least about 5, at least about 10, at leastabout 15, at least about 20, at least about 25, at least about 30, atleast about 35, at least about 40, at least about 45, or at least about50° C. within the subsequent thermal regulation zone 20. Thus, theaverage temperature at the geometric center of the articles withdrawnfrom the last stage of the subsequent thermal regulation zone 20 can beat least about 5, at least about 10, at least about 15, at least about20, at least about 25, at least about 30, at least about 35, at leastabout 40, at least about 45, or at least about 50° C. cooler than theaverage temperature at the geometric center of the articles introducedinto the first stage of the subsequent thermal regulation zone 20.

The average temperature at the geometric center of the articleswithdrawn from the last stage of the subsequent thermal regulation zone20 can be not more than about 120, not more than about 110, not morethan about 100, not more than about 90, not more than about 80, not morethan about 70, not more than about 60, not more than about 50, not morethan about 40° C. lower than the average temperature at the geometriccenter of the articles entering the subsequent thermal regulation zone20. When the articles are being pasteurized, the temperature of thearticles passed through the subsequent thermal regulation zone 20 can bereduced by about 10° C. to about 60° C., or about 20° C. to about 40° C.When the articles are being sterilized, the average temperature at thegeometric center of the articles passed through the subsequent thermalregulation zone 20 can be reduced by about 20° C. to about 120° C. orabout 40° C. to about 60° C.

In certain embodiments, the articles can have an average residence timein the subsequent thermal regulation zone 20 of at least about 5, atleast about 10, at least about 15, at least about 20, at least about 25,at least about 30, at least about 35, at least about 40, at least about45, or at least about 50 minutes and/or not more than about 120, notmore than about 110, not more than about 100, not more than about 90,not more than about 80, not more than about 70, not more than about 60,not more than about 50, or not more than about 40 minutes. When thearticles are being pasteurized, the average residence time of thearticles in the subsequent thermal regulation zone 20 can be in therange of from about 5 minutes to about 60 minutes or about 25 minutes toabout 40 minutes. When the articles are being sterilized, the averageresidence time of the articles in subsequent thermal regulation zone 20can be in the range of from about 15 minutes to about 120 minutes, orabout 50 minutes to about 80 minutes.

In certain embodiments, as generally shown in FIG. 13, the residencetime of the articles in the subsequent thermal regulation zone 20 cancorrespond to, for example, at least about 15, at least about 20, atleast about 25, at least about 30, at least about 35, at least about 40,or at least about 45 percent and/or not more than about 85, not morethan about 80, not more than about 75, not more than about 70, not morethan about 65, or not more than about 60 percent of the total residencetime of the articles passing through the entirety of the liquid contactzone 14. When the articles are being pasteurized, this can correspond toa residence time that is in the range of from 15 percent to 80 percentor 35 percent to 60 percent of the total residence time in liquidcontact zone 14, while, this can correspond to a residence time that isin the range of from 30 percent to 85 percent, or from 45 percent to 75percent of the residence time of the articles in the liquid contact zone14 when the articles are being sterilized.

In certain embodiments, the percent of the total travel path of thearticles defined in the subsequent thermal regulation zone 20 can besimilar and within one or more of the ranges above such as, for example,at least about 15, at least about 20, at least about 25, or at leastabout 30 percent and/or not more than about 75, not more than about 70,not more than about 65, not more than about 60, not more than about 55,or not more than about 50 percent of the total travel path along whichthe articles are transported through the RF heating system may bedefined within the initial thermal regulation zone 16. In some cases,the travel path of the articles through the initial thermal regulationzone 16 can correspond to 15 percent to 75 percent or 30 percent to 55percent of the total travel path of the articles through the entire RFheating system. Depending on whether the articles are being pasteurizedor sterilized, the subsequent thermal regulation zone 20 may have adifferent configuration, as generally shown in FIGS. 2 and 3.

Turning again to FIG. 2, when the articles passing through the RFheating system are being pasteurized, the subsequent thermal regulationzone 20 includes a high-pressure cooling zone 32, a pressure lock 26 b,and a low-pressure cooling zone 34. Articles being pasteurized are notpassed through a hold zone (as shown in FIG. 3), but are insteadtransitioned directly from the RF heating zone 18 into the high-pressurecooling zone 32. In certain embodiments, the articles being pasteurizedcan have an average residence time in a hold zone of not more than about10, not more than about 8, not more than about 6, not more than about 4,not more than about 2, or not more than about 1 minute. Additionally, orin the alternative, not more than about 15, not more than about 12, notmore than about 10, not more than about 8, not more than about 5, notmore than about 2, or not more than about 1 percent of the total travelpath of the articles through the RF heating system may be defined in thehold zone when the articles are being pasteurized.

Overall, the average temperature at the geometric center of the articlesbeing pasteurized changes by not more than about 15, not more than about10, not more than about 5, not more than about 2, or not more than about1° C. as it passes through a hold zone. The temperature of at leastabout 95, at least about 98, or at least about 99 percent of the totalvolume of the articles being pasteurized withdrawn from the hold zone,if present, can be within a temperature range of about 2.5, about 2,about 1.5, about 1, about 0.75, about 0.50, or about 0.25° C. Thehigh-pressure cooling zone 34 and the low-pressure cooling zone 32 willbe discussed in further detail below.

Turning now to FIG. 3, when the articles passed through the RF heatingsystem 10 are being sterilized, the subsequent thermal regulation zone20 includes a thermal isolation zone 28, a hold zone 30, a high-pressurecooling zone 32, a pressure lock 26 b, and a low-pressure cooling zone34. Articles exiting the RF heating zone 18 may be passed through athermal isolation zone 28 before entering the hold zone 30. In certainembodiments, the temperature of the fluid (e.g., liquid medium ifliquid-filled) in the hold zone 30 may be at least about 2, at leastabout 5, at least about 8, at least about 10, at least about 12, atleast about 15, at least about 18, or at least about 20° C. higher thanthe average temperature of the fluid (e.g., liquid medium ifliquid-filled) in the RF heating zone 18. The thermal isolation zone 28may be configured to transition the articles from the RF heating zone 18to the hold zone 30 while maintaining the difference in temperaturebetween the two zones.

Turning now to FIG. 30, one embodiment of a thermal isolation zone 530is shown as generally comprising a transport housing 520 and a movablearticle transport device 522 disposed within the transport housing 520.As generally shown in FIG. 30, articles 100 exiting RF heating zone maybe moved toward the thermal isolation zone 530 using a convey line 570disposed within a first vessel 550. In some embodiments, the convey line570 shown in FIG. 30 may be the take-away conveyor discussed previously.When the articles 100 reach the thermal isolation zone 530, one or moreof the articles 100 can be loaded into an inlet of the movable articletransport device 522. In some cases, the articles 100 may be loadedusing the convey line 570, or may be pushed into the movable articletransport device 522 using a pusher (not shown).

Once the articles 100 are loaded, the movable article transport device522 may move within the transport housing 520 so that the movablearticle transport device 522 aligns with a second convey line 572disposed within (or just upstream) of the hold zone in a second vessel552. At that point, a pusher arm 574 or other device may be used tounload the article or articles 100 from an outlet of the movable articletransport device 522 and onto the second convey line 572. Thereafter,the articles 100 may be transported into the hold zone for furtherprocessing, while the empty movable article transport device 522 isreturned to the its original position proximate the first convey line570 in vessel 550. Although shown in FIG. 30 as moving downwardly fromthe first convey line 570 to the second convey line 572, it should beunderstood that the transport housing 530 could be configured so thatthe movable article transport device 522 moves upwardly if, for example,the second vessel 552 was located at a higher vertical elevation thanthe first vessel 550.

Referring again to FIG. 3, in the hold zone 30, the heated articles areheld so that the temperature of each article is maintained at or above aspecified minimum temperature for a certain amount of time. In certainembodiments, the temperature at the geometric center of each articlepassing through the hold zone 30 can be maintained at a temperature ator above the average temperature at the geometric center of the articlesexiting the RF heating zone 18. As a result, the articles exiting thehold zone 30 may be sufficiently and uniformly sterilized.

In certain embodiments, articles passing through hold zone 30 may becontacted with a liquid during at least a portion of the holding step.The liquid may comprise or be water and can have a temperature withinabout 25, within about 20, within about 15, or within about 10° C. ofthe average temperature at the geometric center of the articlesintroduced into the hold zone 30. The step of contacting may includesubmerging the articles in a liquid medium and/or contacting at least aportion of the articles with a jet of liquid emitted from one or morespray nozzles within the hold zone 30.

Overall, the average temperature at the geometric center of the articlespassing through the hold zone 30 may increase by at least about 2, atleast about 4, at least about 5, at least about 8, at least about 10, orat least about 12° C. and/or not more than about 40, not more than about35, not more than about 30, not more than about 25, or not more thanabout 20° C., or it may increase by about 4° C. to about 40° C., orabout 10° C. to about 20° C. In certain embodiments, the articleswithdrawn from the hold zone 30 can be uniformly heated so that, forexample, the temperature of at least about 95, at least about 98, or atleast about 99 percent of the total volume of the articles can be withina temperature range of about 2.5, about 2, about 1.5, about 1, about0.75, about 0.50, or about 0.25° C.

In certain embodiments, the average residence time of each articlepassed through the hold zone 30 (e.g., the hold time) can be at leastabout 1, at least about 2, at least about 5, at least about 6, or atleast about 8 minutes and/or not more than about 40, not more than about35, not more than about 30, not more than about 25, not more than about20, not more than about 15, or not more than about 10 minutes, or it canbe in the range of from 2 minutes to 40 minutes or 6 minutes to 20minutes.

Turning again to FIG. 13, the average residence time of the articlespassing through the hold zone 30 during sterilization can be at leastabout 2, at least about 5, at least about 8, or at least about 10percent and/or not more than about 50, not more than about 45, not morethan about 40, not more than about 35, not more than about 30, not morethan about 25, or not more than about 20 percent of the overallresidence time of the articles passing through liquid contact zone 14.In some embodiments, the average residence time of the articles passingthrough the RF heating zone 18 can be at least about 2, at least about5, at least about 8, or at least about 10 percent and/or not more thanabout 50, not more than about 45, not more than about 40, not more thanabout 35, or not more than about 30 percent of the average residencetime of the articles in the hold zone 30. At least about 5, at leastabout 8, at least about 10 percent and/or not more than about 50, notmore than about 40, not more than about 30, or not more than about 20percent of the total article travel path may be defined within the holdzone 30.

The articles passed through the hold zone 30 may be transported usingone or more convey lines. Any suitable type of conveyor may be used toform the convey line through hold zone 30 including, for example, ahelical conveyor as described previously with respect to FIGS. 7 through10. Other types of conveyors may also be used. In certain embodiments,the convey line used to move the articles through the hold zone 30 cancomprise at least one indexing conveyor, which may permit the residencetime of the articles passing through hold zone 30 to be adjusted. Theability to control and adjust the article residence time and/orprocessing rate within the hold zone 30, or in other sections of the RFheating system, may provide additional operational flexibility notpossible with other types of commercial heating systems.

Turning now to FIGS. 31 and 32, embodiments of one section of amulti-zone processing apparatus that has enhanced operationalflexibility are shown. Such apparatuses can be used, for example, in thesection of an RF heating system that includes the hold zone 30. Theapparatus shown in FIGS. 31 and 32 includes sequential first, second,and third processing zones that each including separate conveyors fortransporting articles through that zone. In the embodiments depicted inFIGS. 31 and 32, the first zone includes an initial continuous conveyor710, the second zone includes an indexing conveyor 730, and the thirdzone includes a subsequent continuous conveyor 720. In addition to thesection of the RF heating system that includes the hold zone 30, thisarrangement of conveyors can also be used in other zones of the RFheating system, including, the thermal equilibration zone 24, the RFheating zone 18, the high-pressure cooling zone 32, or the low-pressurecooling zone 34. Such an arrangement may also be used in other types ofsystems for treating articles that include multiple processing zones.

In operation, a plurality of discrete articles 100 can be transportedthrough the first zone using the initial continuous conveyor 710. Insome embodiments, the first zone may be a process zone, such as the RFheating zone 18 or the loading zone 12, while, in other embodiments, itmay be a transition zone, such as the thermal isolation zone 28 disposedbetween the RF heating zone 18 and the hold zone 30. At the end of thefirst zone, the articles 100 may be transitioned from the initialcontinuous conveyor 710 to the indexing conveyor 730 of the second zone.The indexing conveyor 730 generally includes a plurality of discretearticle-receiving spaces 732 defined along the convey path of theindexing conveyor 730 for receiving and holding articles passing throughthe second zone. The articles are transitioned onto the indexingconveyor 730 from the initial continuous conveyor 710 by intermittentlyloading individual articles 100 from the initial continuous conveyor 710into individual article-receiving spaces 732 of the indexing conveyor730. In certain embodiments, the indexing conveyor 730 may include Ntotal article-receiving spaces 732, wherein N is an integer between 4and 500. In some embodiments, N can be in the range of from 5 to 250, 10to 100, or 20 to 80. The indexing conveyor 730 can be any suitable typeof conveyor, including, for example, a trough conveyor as shown in FIG.31 or a helical conveyor as shown in FIG. 32.

Once loaded into the indexing conveyor 730, the articles 100 may betransported through the second zone. The second zone may be a processzone, such as, for example the hold zone 30, or it could be another athermal regulation zone, such as the thermal equilibration zone 24, thehigh-pressure cooling zone 32, or the low-pressure cooling zone 34. Thesecond zone may also be the RF heating zone 18. Articles 100 passedthrough the second zone may be intermittently moved along the conveypath of the indexing conveyor 730. The convey path can be substantiallylinear such as, for example, when the indexing conveyor 730 is a trough(or other similar) conveyor as shown in FIG. 31, or it can besubstantially helical such as, for example, when the indexing conveyor730 is a helical conveyor, as generally shown in FIG. 32.

As shown in FIGS. 31 and 32, the indexing conveyor 730 can include anarticle-guiding track 734 and a plurality of article pusher members 736,adjacent ones of which form the article-receiving spaces 732. As thearticles 100 travel along the convey path of the indexing conveyor 730,they may be moved along the article-guiding track 734 using the articlepusher members 736. When the conveyor is a trough conveyor as shown, forexample, in FIG. 31, the article pusher members 736 may comprise pushtabs. When the conveyor is a helical conveyor as generally shown in FIG.32, the article pusher members 736 may be vertical push rods asdescribed previously with respect to FIGS. 7 through 10. When theindexing conveyor 730 is a helical conveyor, the article pusher members736 may rotate on an axis of rotation that corresponds to the centralaxis of the helical convey path.

After being transported along the convey path of the indexing conveyor730, the articles 100 may be transitioned from the indexing conveyor 730to the subsequent continuous conveyor 720 by intermittently unloadingindividual articles 100 from each of the article-receiving spaces 732 ofthe indexing conveyor 730. The subsequent continuous conveyor 720 maythen transport the articles 100 through a third zone, which can be aprocess zone (such as the RF heating zone 18 or the high-pressurecooling zone 32 or the low-pressure cooling zone 34), or a transitionzone between two different process zones.

In some embodiments, the average residence time of the articles 100 inthe second zone may be adjusted by changing the average number ofarticles on the convey path of the indexing conveyor 730. For example,in some embodiments, when the articles are being transitioned from theinitial continuous conveyor 710 to the indexing conveyor 730, one ormore of the article-receiving spaces 732 of the indexing conveyor 730may be skipped, so that one or more of the article-receiving spaces 732remains empty as the articles pass through the second zone. As a result,the total number of articles on the convey path of the indexing conveyoris less than N, and the residence time of each article 100 in the secondzone is less than it would be if N articles were present. In some cases,the rate of unloading from the initial continuous conveyor 710 to theindexing conveyor 730 and/or the rate of unloading from the indexingconveyor 730 to the subsequent continuous conveyor 720 may remain thesame, or approximately the same, despite changes to the residence timeof the articles 100 passed along the indexing conveyor 730.

In certain embodiments, the residence time of the articles in the first,second, and third zones can be controlled using a process controlsystem. An example of the basic components of a process control system740 shown in FIGS. 31 and 32 includes a computer 750, a processcontroller 752, and a plurality of drivers 754, 756, and 758 forcontrolling the movement of the initial continuous conveyor 710, theindexing conveyor 730, and the subsequent continuous conveyor 720,respectively. The computer 750 can be configured to receive input from auser and, based on that input (or the results of calculations using thatinput), to generate and transmit an output signal 751 to the processcontroller 752. Alternatively, the process controller 752 may beintegral with the computer 750 as a single process control device. Theprocess controller 752 converts the input signal 751 into one or moreoutput signals, shown as signals 753, 755, and 757 in FIGS. 31 and 32,which regulate the motion of the drivers 754, 756, and 758,respectively. As a result, the speed and/or frequency of movement of oneor more of the initial continuous conveyor 710, the indexing conveyor730, and the subsequent continuous conveyor 720 can be automaticallycontrolled by the process control system 740.

In operation, a user may input residence time and processing rateinformation into the computer 750. In certain embodiments, thatinformation can be used by the process control system 740 to calculateone or more operating parameters for the system. In certain embodiments,the operating parameter calculated by the computer 750 and/or processcontroller 752 of the process control system 740 can include a loadingparameter that determines the number of the article receiving spaces 732are skipped while the articles 100 are loaded from the initialcontinuous conveyor 710 onto the indexing conveyor 730. The processcontrol system 740 can then operate the first, second, and third zonesby, for example, controlling the motion of the initial continuousconveyor 710, the subsequent continuous conveyor 720, and/or indexingconveyor 730 based on the calculated operating parameters as thearticles are transported through each zone.

Subsequently, a user may input different processing rate and differentresidence time information into the computer 750 of the process controlsystem 740 so that the computer 750 and/or process controller 752calculates a different loading parameter than was previously calculated.This can, for example, results in a new loading parameter that requiresa different number of article receiving spaces 732 to be skipped duringloading. As a result, when the process control system 740 operates thefirst, second, and third zones according to the new parameters, thefrequency at which the article-receiving spaces 732 of the indexingconveyor 730 are skipped can be reduced or increased as dictated by thenew loading parameter. As a result, the residence time of the articlesin the second zone increases or decreases. In particular, reducing thefrequency at which the article-receiving spaces 732 are skipped duringloading can increase the average residence time of the articles 100 inthe second zone, while increasing the frequency at which thearticle-receiving spaces 732 are skipped during loading decreases theaverage residence time of the articles 100 in the second zone. Thus, incertain embodiments, by entering different processing rate and residencetime information into the process control system 740, the user maychange the residence time of the articles in the second process zone.

By changing the frequency at which the article-receiving spaces areskipped, the process may transition from an initial operating mode to asubsequent operating mode. In transitioning from one mode to another,the residence time of the articles 100 in the second zone may be changedrelative to the residence time of the articles 100 in the first and/orthird zones. For example, in the initial operating mode, the articlesmay have an average residence time in the first, second, and third zonesof T1 i, T2 i, and T3 i, respectively, while the articles may have anaverage residence time in the first, second, and third zones of T1 s, T2s, and T3 s, when the process is operating in the subsequent mode.Actual values for each of T1 i, T2 i, T3 i, T1 s, T2 s, and T3 s dependon the specific zone and can fall within one or more of the rangesprovided herein. In some embodiments, the ratio of T2 s to T1 s (T2 s/T1s) can be at least about 5, at least about 10, at least about 15, atleast about 20, or at least about 25 percent different than the ratio ofT2 i to T1 i (T2 i/T1 i). Alternatively, or in addition, the ratio of T2s to T3 s (T2 s/T3 s) can be at least about 5, at least about 10, atleast about 15, at least about 20, or at least about 25 percentdifferent than the ratio of T2 i to T3 i (T2 i/T3 i).

When the process is transitioned from the initial mode to the subsequentmode by increasing the frequency at which the article receiving spaces732 are skipped, the total number of articles on the convey path on theindexing conveyor is reduced. As a result, the average residence time ofeach article 100 in the second zone decreases relative to the averageresidence time of the articles in the first and/or third zones. Incertain embodiments, the result can be that the ratio of T2 s/T1 s canbe at least about 5 percent less than T2 i/T1 i and/or the ratio of T2s/T3 s can be at least about 5 percent less than the ratio of T2 i/T3 i.In certain embodiments, T2 s/T1 s can be at least about 10, at leastabout 15, at least about 20, or at least about 25 percent less than T2i/T1 i and/or T2 s/T3 s can be at least about 10, at least about 15, atleast about 20, or at least about 25 percent less than T2 i/T3 i.

When the process is transitioned from the initial mode to the subsequentmode by decreasing the frequency at which the article receiving spaces732 are skipped, the total number of articles on the convey path on theindexing conveyor is increased. As a result, the average residence timeof each article in the second zone increases relative to the averageresidence time of the articles in the first and/or third zones. Incertain embodiments, the result can be that the ratio of T2 s/T1 s canbe at least about 5 percent greater than T2 i/T1 i and/or the ratio ofT2 s/T3 s can be at least about 5 percent greater than the ratio of T2i/T3 i. In certain embodiments, T2 s/T1 s can be at least about 10, atleast about 15, at least about 20, or at least about 25 percent greaterthan T2 i/T1 i and/or T2 s/T3 s can be at least about 10, at least about15, at least about 20, or at least about 25 percent greater than T2 i/T3i.

In some embodiments, when the average residence time of the articles inthe second zone is adjusted relative to the average residence time ofthe articles in the first and/or third zones, the overall rate ofarticles passing through the first, second, and third zones may remainconstant. For example, during the initial operating mode, the articlesmay pass through the first, second, and third zones at an initialaverage rate of Ri articles per minute. During the subsequent operatingmode, the articles may pass through the first, second, and third zonesat a subsequent average rate of Rs articles per minute. In certainembodiments, Ri is within about 25, within about 20, within about 15,within about 10, or within about 5 percent of Rs, or Ri can be equal toRs. It should be understood that the process could be operated in anynumber of modes, and the terms “initial” and “subsequent” are used forreference, not necessarily to limit the processes or systems herein totwo distinct modes of operation.

Turning again to FIGS. 2 and 3, articles being pasteurized that areremoved from the RF heating zone 18, and articles being sterilizedremoved from the hold zone 30 may be introduced into the high-pressurecooling zone 32. In the high-pressure cooling zone 32 the averagetemperature at the geometric center of the articles can be reduced by atleast about 5, at least about 10, at least about 15, or at least about20° C. and/or not more than about 60, not more than about 55, not morethan about 50, not more than about 45, not more than about 40, not morethan about 35, or not more than about 30° C. When the articles are beingpasteurized, the average temperature at the geometric center of thearticles can be reduced by about 5° C. to about 40° C. or about 10° C.to about 30° C. When the articles are being sterilized, the averagetemperature at the geometric center of the articles can be reduced byabout 10° C. to about 60° C., or about 20° C. to about 40° C. as thearticles pass through the high-pressure cooling zone 32.

Articles introduced into the high-pressure cooling zone 32 can have anaverage temperature at the geometric center of at least about 80, atleast about 85, at least about 90, at least about 95, at least about100, at least about 105, at least about 110, at least about 115, or atleast about 120° C. and/or not more than about 135, not more than about130, not more than about 125, not more than about 120, not more thanabout 115, not more than about 110, or not more than about 105° C. Whenthe articles are being pasteurized and are introduced into thehigh-pressure cooling zone 32 from the RF heating zone 18, the averagetemperature at the geometric center of the articles can be in the rangeof from about 80° C. to about 115° C., or about 95° C. to about 105° C.When the articles are being sterilized and are introduced into thehigh-pressure cooling zone 32 from the hold zone 30, the averagetemperature at the geometric center of the articles can be in the rangeof from about 110° C. to about 135° C. or about 120° C. to about 130° C.The average difference between the maximum temperature (i.e., hottestportion) and the minimum temperature (i.e., coldest portion) of eacharticle exiting the RF heating zone 18 or hold zone 30 can be not morethan about 5, not more than about 2.5, not more than about 2, not morethan about 1.5, not more than about 1, or not more than about 0.5° C.

In certain embodiments, the hold zone 30 can have a pressure of at leastabout 2, at least about 5, at least about 10, or at least about 15 psigand/or not more than about 80, not more than about 75, not more thanabout 70, not more than about 65, not more than about 60, not more thanabout 55, not more than about 50, not more than about 45, not more thanabout 40, not more than about 35, not more than about 30, not more thanabout 25, not more than about 20 psig.

The average residence time of the articles passing through thehigh-pressure cooling zone 32 can be at least about 1, at least about 2,at least about 5, or at least about 10 minutes and/or not more thanabout 60, not more than about 55, not more than about 50, not more thanabout 45, not more than about 40, not more than about 35, not more thanabout 30, not more than about 25, not more than about 20, not more thanabout 15, or not more than about 10 minutes. When the articles passedthrough the high-pressure cooling zone 32 are being pasteurized, theaverage residence time of the articles in high-pressure cooling zone 32can be in the range of from about 1 minute to about 30 minutes, or about5 minutes to about 10 minutes. When the articles are being sterilized,the average residence time of the articles passing through thehigh-pressure cooling zone 32 can be in the range of from about 2 toabout 60 minutes, or about 10 to about 20 minutes.

Referring again to FIG. 13, the average residence time of the articlespassing through the high-pressure cooling zone 32 makes up a portion ofthe residence time of the articles passing through the liquid contactzone. For example, in some embodiments, the average residence time ofthe articles passing through the high-pressure cooling zone 32 can be atleast about 4, at least about 5, at least about 8, or at least about 10percent and/or not more than about 50, not more than about 45, not morethan about 40, not more than about 35, not more than about 30, or notmore than about 25 percent of the total residence time of the articlespassing through liquid contact zone 14. This can correspond to a travelpath through the high-pressure cooling zone 32 that is at least about 4,at least about 5, at least about 8, or at least about 10 percent and/ornot more than about 50, not more than about 40, not more than about 30,not more than about 25, or not more than about 20 percent of the totaltravel path of the articles moving through the RF heating system. Thetravel path of the articles through the high-pressure cooling zone 32can be in the range of from about 4 to about 50 percent, or about 10 toabout 25 percent of the total travel path the articles follow whenmoving through the RF heating system.

When the articles heated in the RF heating system are being sterilized,the residence time of the articles in the hold zone 30 can be less than,similar to, or greater than the residence time of the articles in thehigh-pressure cooling zone 32. For example, in certain embodiments, theaverage residence time of the articles passing through the hold zone 30can be at least about 5, at least about 10, at least about 15, at leastabout 20, at least about 25, at least about 30, at least about 35, atleast about 40, at least about 45, or at least about 50 percent and/ornot more than about 400, not more than about 300, not more than about200, not more than about 150 percent of the average residence time ofthe articles passing through the high-pressure cooling zone 32.

When the articles are being pasteurized (and are not passed through ahold zone), the residence time of articles passing through the hold zonecan be not more than about 25, not more than about 20, not more thanabout 15, not more than about 10, or not more than about 5 percent ofthe residence time of the articles passing through the high-pressurecooling zone 32. When the articles are being sterilized, the residencetime of the articles passing through the hold zone 30 can be in therange of from about 25 percent to about 400 percent, or about 50 percentto about 150 percent of the average residence time of the articlespassing through the high-pressure cooling zone 32.

Articles passing through the high-pressure cooling zone 32 may becontacted with a liquid during at least a portion of the cooling step.The liquid may comprise or be water and can have a temperature withinabout 25, within about 20, within about 15, or within about 10° C. ofthe average temperature at the geometric center of the articleswithdrawn from the outlet of the high-pressure cooling zone 32. The stepof contacting may include submerging the articles in a liquid mediumand/or contacting at least a portion of the articles with a jet ofliquid emitted from one or more spray nozzles within the high-pressurecooling zone 32.

In certain embodiments, the articles may be passed through thehigh-pressure cooling zone 32 using at least one conveyor. Any suitabletype of conveyor can be used and, in some embodiments, it may compriseat least one helical conveyor as described previously with respect toFIGS. 7 through 10. In certain embodiments, when the articles beingheated are sterilized, the convey line in the hold zone 30 and thehigh-pressure cooling zone 32 can each comprise helical conveyors,configured so that one of the conveyors transports the articles upwardlyfrom the inlet to the outlet of the conveyor and the other of theconveyors transports the articles downwardly from the inlet to theoutlet of the conveyor. One example of such a configuration is shown inFIG. 33.

As shown in FIG. 33, the vessel 620 used in hold zone 30 houses ahelical conveyor 622 for transporting articles 100 from a lower inlet624 configured to receive articles into the vessel 620 to an upperoutlet 626 configured to discharge articles from the vessel 620, whilethe vessel 630 used in high-pressure cooling zone 32 includes anotherhelical conveyor 632 disposed therein and configured to transportarticles 100 from an upper inlet 634 configured to receive articles to alower outlet 636 configured to discharge articles. Each conveyor 620 and630 include respective helical tracks 646 and 648 that extend aroundrespective central vertical axes 653 and 655, which are horizontallyoffset from one another. It should be understood that helical conveyors622 and 632 are shown schematically in FIG. 33 and would include avariety of other elements, such as article pushers and liquid heattransfer systems, as described previously with respect to FIGS. 7through 10. Further, although shown as being received in two separatevessels 620 and 630, it should also be understood that both conveyorsmay be housed in a single vessel. In such an embodiment, the articles100 passing along the conveyors 620 and 630 would be introduced into thevessel by inlet 624 and removed from the vessel by outlet 636, both ofwhich would be located at a similar, or substantially the same, verticalelevation.

In certain embodiments, when the hold zone 30 and the high-pressurecooling zone 32 are at least partially liquid filled, the averagetemperature of the liquid in the hold zone 30 can be at least about 20,at least about 25, at least about 30, at least about 35, at least about40, at least about 45, at least about 50, at least about 55, at leastabout 60, at least about 65, at least about 70, at least about 75, atleast about 80, at least about 85, at least about 90, at least about 95,or at least about 100° C. and/or not more than about 200, not more thanabout 190, not more than about 180, not more than about 170, not morethan about 160, not more than about 150, not more than about 140, notmore than about 130, not more than about 120, not more than about 110,not more than about 100, or not more than about 90° C. higher than theaverage temperature of the liquid in the high-pressure cooling zone 32.Additionally, or in the alternative, the pressures of the hold zone 30and the high-pressure cooling zone 32 may be within about 10, withinabout 5, within about 2, or within about 1 psig of one another.

As discussed previously, articles 100 traveling along the helicalconveyor 622 in hold zone 30 and/or articles 100 traveling along thehelical conveyor 632 in the high-pressure cooling zone 32 shown in FIG.33 may be contacted with a liquid during at least a portion of thetravel path. In certain embodiments, the contacting performed in one orboth steps may include submerging the articles 100 in a liquid medium.Additionally, or in the alternative, the articles 100 may also becontacted with a spray of liquid discharged from one or more liquid jets(not shown) located within vessel 620 and/or vessel 630. In otherembodiments, a different type of conveyor may be used in one of holdzone 30 and/or high-pressure cooling zone 32.

As shown in FIGS. 2 and 3, the articles exiting the high-pressurecooling zone 32 can be passed through another pressure lock 26 b beforeentering the low-pressure cooling zone 34. Similarly to pressure lock 26a described previously with respect to FIGS. 11 and 12, the pressurelock 26 b can be configured to transition the articles between twoenvironments having different pressures. Pressure lock 26 a shown inFIGS. 2 and 3 may be configured to transition the articles from ahigher-pressure environment to a lower-pressure environment, such as,for example, from the high-pressure cooling zone 32 to the low-pressurecooling zone 34. In certain embodiments, the high-pressure cooling zone32 can have a pressure that is at least about 2, at least about 5, atleast about 10, or at least about 15 psig and/or not more than about 50,not more than about 40, not more than about 30, not more than about 20,or not more than about 10 psig higher than the pressure in high-pressurecooling zone 32.

Low-pressure cooling zone 34 may be configured to reduce the temperatureat the geometric center of the articles by at least about 5, at leastabout 10, at least about 15, at least about 20, at least about 25, atleast about 30, at least about 35, or at least about 40° C. and/or notmore than about 100, not more than about 95, not more than about 90, notmore than about 85, not more than about 80, not more than about 75, notmore than about 70, not more than about 65, not more than about 60, ornot more than about 55° C. When the articles are being pasteurized, thelow-pressure cooling zone 34 may reduce the temperature at the geometriccenter of the articles passing therethrough by about 5° C. to about 100°C. or about 50° C. to about 80° C. When the articles are beingsterilized, the low-pressure cooling zone 34 may reduce the temperatureat the geometric center of the articles by about 10° C. to about 75° C.or about 40° C. to about 60° C.

When removed from the low-pressure cooling zone 34, the articles may beat a suitable handling temperature. For example, the temperature at thegeometric center of the articles exiting the low-pressure cooling zone34 can be at least about 50, at least about 55, at least about 60, atleast about 65, at least about 70, at least about 75, or at least about80° C. and/or not more than about 100, not more than about 97, not morethan about 95, not more than about 90, or not more than about 85° C.When being pasteurized, the articles withdrawn from the low-pressurecooling zone 34 can have an average temperature at the geometric centerin the range of from about 50° C. to about 97° C. or about 80° C. toabout 95° C. When being sterilized, the average temperature at thegeometric center of the articles exiting the low-pressure cooling zone34 can be about 50° C. to about 100° C. or about 80° C. to about 97° C.The average difference between the maximum temperature (i.e., hottestportion) and the minimum temperature (i.e., coldest portion) of eacharticle exiting the low-pressure cooling zone can be not more than about5, not more than about 2.5, not more than about 2, not more than about1.5, not more than about 1, or not more than about 0.5° C.

The average residence time of the articles passing through thelow-pressure cooling zone 34 can be at least about 1, at least about 2,at least about 5, at least about 8, at least about 10, at least about12, or at least about 15 minutes and/or not more than about 80, not morethan about 70, not more than about 60, not more than about 50, not morethan about 40, not more than about 30, or not more than about 20minutes. When the articles are being pasteurized, the average residencetime of the articles in the low-pressure cooling zone 34 can be in therange of from about 1 minute to about 80 minutes, or about 5 minutes toabout 20 minutes. When the articles are being sterilized, the averageresidence time of the articles in the low-pressure cooling zone 34 canbe in the range of from about 2 minutes to about 80 minutes or about 15minutes to about 40 minutes.

This can correspond to at least about 5, at least about 10, at leastabout 15, or at least about 20 percent and/or not more than about 60,not more than about 55, not more than about 50, not more than about 40percent of the total residence time of the articles in the liquidcontact zone 14, or the average residence time of the articles inlow-pressure cooling zone 34 can be in the range of from about 5 percentto about 60 percent or about 20 percent to about 40 percent of the totalresidence time of the articles in the RF heating system. In certainembodiments, the travel path of the articles through the low-pressurecooling zone 34 can reflect similar percentages of the total travel pathof the articles through the RF heating system.

In certain embodiments, the average residence time of the articles inthe high-pressure cooling zone 32 can be less than, similar to, orgreater than the average residence time of the articles in thelow-pressure cooling zone 34. For example, the average residence time ofthe articles in the high-pressure cooling zone 32 can be at least about25, at least about 30, at least about 35, or at least about 40 percentand/or not more than about 400, not more than about 350, not more thanabout 300, not more than about 250, not more than about 200, not morethan about 150, or not more than about 120 percent of the averageresidence time of the articles in the low-pressure cooling zone 34. Theaverage residence time of the articles in the high-pressure cooling zone32 can be in the range of from about 25 percent to about 400 percent, orabout 40 percent to about 120 percent of the average residence time ofthe articles in the low-pressure cooling zone 34.

In certain embodiments, the articles may be passed through thelow-pressure cooling zone 34 using at least one conveyor. Any suitabletype of conveyor can be used and, in some embodiments, it may compriseat least one helical conveyor as described previously with respect toFIGS. 7 through 10. Alternatively, one or more other types of conveyorsmay be used according to other embodiments of the present invention. Insome cases, at least one, at least two, or all of the hold zone 30 (whenpresent), the high-pressure cooling zone 32, and the low-pressurecooling zone 34 may include at least one helical conveyor.

As shown in FIG. 1, the cooled articles exiting the low-pressure coolingzone 34 may be removed from the RF heating system 10 via an unloadingzone 22. Any suitable method or device may be used to remove thearticles from contact with liquid in unloading zone 22. The temperatureat the geometric center of the articles removed from the unloading zone22 can be at least about 25, at least about 30, at least about 35, atleast about 40, at least about 45, or at least about 50° C. and/or notmore than about 80, not more than about 75, not more than about 70, notmore than about 65, or not more than about 60° C. The unloading zone maybe operated at approximately ambient temperature and/or pressure. Onceremoved from the unloading zone 22, the articles may be transported forfurther processing, storage, shipment, or use.

Definitions

As used herein, the terms “comprising,” “comprises,” and “comprise” areopen-ended transition terms used to transition from a subject recitedbefore the term to one or more elements recited after the term, wherethe element or elements listed after the transition term are notnecessarily the only elements that make up the subject.

As used herein, the terms “including,” “includes,” and “include” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “having,” “has,” and “have” have the sameopen-ended meaning as “comprising,” “comprises,” and “comprise.”

As used herein, the terms “containing,” “contains,” and “contain” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “a,” “an,” “the,” and “said” mean one or more.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itselfor any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

The preferred forms of the invention described above are to be used asillustration only, and should not be used in a limiting sense tointerpret the scope of the present invention. Obvious modifications tothe exemplary embodiments, set forth above, could be readily made bythose skilled in the art without departing from the spirit of thepresent invention.

The inventor hereby states his intention to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of thepresent invention as pertains to any method or apparatus departing frombut not outside the literal scope of the invention as set forth in thefollowing claims.

I claim:
 1. A process for sterilizing or pasteurizing articles usingradio frequency (RF) energy, said process comprising: (a) passing aplurality of articles through a liquid contact zone of an RF heatingsystem on at least one convey line while maintaining said articles incontact with a liquid during at least a portion of said passing, whereinsaid liquid contact zone includes an initial thermal regulation zone, anRF heating zone, and a subsequent thermal regulation zone; (b)regulating the temperature of said articles on said convey line in saidinitial thermal regulation zone to promote temperature uniformity ofsaid articles; (c) subsequent to said regulating of step (b), heatingsaid articles on said convey line with RF energy in said RF heating zoneto thereby increase the average temperature at the geometric center ofsaid articles by at least 20° C.; and (d) subsequent to said heating ofstep (c), regulating the temperature of said articles on said conveyline to thereby decrease the average temperature at the geometric centerof said articles by at least 10° C., wherein the average residence timeof said articles in said RF heating zone is not more than 10 percent ofthe average residence time of said articles in said liquid contact zone.2. The process of claim 1, wherein the average difference between themaximum and minimum temperatures within each of said articles exitingsaid RF heating zone is not more than 20° C.
 3. The process of claim 1,wherein the average difference between the temperatures at the geometriccenters of adjacent articles exiting said RF heating zone is not morethan 2° C.
 4. The process of claim 1, wherein the average temperature ofat least 95 percent of the volume of said articles exiting said RFheating zone is within a 10° C. temperature range.
 5. The process ofclaim 1, wherein the average temperature at the geometric center of saidarticles exiting said RF heating zone is at least 90° C.
 6. The processof claim 1, wherein said articles pass through said RF heating zone at arate of at least 10 articles per minute and a velocity of at least 0.10inches per second, wherein the travel path of each of said articlesthrough said RF heating zone has a length of not more than 20 feet, andwherein the average residence time of said articles in said RF heatingzone is in the range of 0.5 to 6 minutes, wherein the average residencetime of said articles in said liquid contact zone is in the range of 20to 240 minutes.
 7. The process of claim 1, wherein said articles have adielectric constant in the range of 20 to 150 and a dielectric lossfactor in the range of 10 to 1500, wherein said articles have a volumeof at least 8 cubic inches.
 8. The process of claim 1, wherein saidheating of step (c) increases the average temperature at the geometriccenter of said articles by at least 40° C. to a temperature of at least100° C., wherein the average difference between the maximum and minimumtemperatures within each of said articles exiting said RF heating zoneis not more than 10° C., wherein the average difference between thetemperatures at the geometric centers of adjacent articles exiting saidRF heating zone is not more than 1° C., wherein the average temperatureof at least 95 percent of the volume of each of said articles exitingsaid RF heating zone is within a 2.5° C. temperature range, wherein theaverage residence time of said articles in said RF heating zone is notmore than 5 percent of the average residence time of said articles insaid liquid contact zone, wherein the average residence time of saidarticles in said liquid contact zone is in the range of 40 to 120minutes, wherein said articles pass through said RF heating zone at arate of at least 25 articles per minute, wherein said articles passthrough said RF heating zone at a velocity of at least 0.15 inches persecond, wherein the travel path of each of said articles through said RFheating zone has a length of not more than 10 feet, wherein saidarticles have a dielectric constant in the range of 30 to 100 and adielectric loss factor in the range of 100 to 1250, wherein each of saidarticles has a volume of at least 15 cubic inches, wherein each of saidarticles is a foodstuff contained in a sealed package, wherein saidliquid is water.
 9. The process of claim 1, wherein said subsequentthermal regulation zone includes a hold zone and at least one coolingzone downline of said hold zone, wherein the average temperature at thegeometric center of said articles in said hold zone is maintained at orabove the average temperature at the geometric center of said articlesexiting said RF heating zone, wherein the average residence time of saidarticles in said RF heating zone is 5 to 50 percent of the averageresidence time of said articles in said hold zone.
 10. The process ofclaim 1, wherein said articles are submerged in said liquid during atleast a portion of said heating in said RF heating zone, wherein saidheating includes transmitting RF energy toward said RF heating zonethrough a liquid-filled waveguide located outside of said RF heatingzone, wherein said liquid-filled waveguide is filled with the sameliquid in which said articles in said RF heating zone are submerged. 11.The process of claim 1, wherein said convey line comprises at least onehelical conveyor in said initial thermal regulation zone and at leastone helical conveyor in said subsequent thermal regulation zone.
 12. Theprocess of claim 1, wherein said RF heating zone is defined within asplit applicator, wherein said split applicator comprises spaced apartupper and lower applicator sections, wherein a resonant cavity is formedwithin said split applicator during said RF heating, wherein said conveyline comprises a swing arm conveyor having a plurality ofarticle-engaging convey arms that pass through the space between saidupper and lower sections of said split applicator while conveying saidarticles through said RF heating zone.
 13. A process for sterilizing orpasteurizing articles using radio frequency (RF) energy, said processcomprising: (a) passing a plurality of articles through a liquid contactzone of an RF heating system on at least one convey line whilemaintaining said articles in contact with a liquid during at least aportion of said passing, wherein said liquid contact zone includes aninitial thermal regulation zone, an RF heating zone, and a subsequentthermal regulation zone; (b) regulating the temperature of said articleson said convey line in said initial thermal regulation zone to promotetemperature uniformity of said articles; (c) subsequent to saidregulating of step (b), heating said articles on said convey line withRF energy in said RF heating zone to thereby increase the averagetemperature at the geometric center of said articles by at least 20° C.;and (d) subsequent to said heating of step (c), regulating thetemperature of said articles on said convey line to thereby decrease theaverage temperature at the geometric center of said articles by at least10° C., wherein said articles travel through said liquid contact zone ona nonlinear travel path having a total length that is at least 10 timesgreater than the linear distance between the locations where saidarticles enter and exit said liquid contact zone.
 14. The process ofclaim 13, wherein said total length of said travel path is at least1,000 feet.
 15. The process of claim 14, wherein the length of saidtravel path through said RF heating zone is not more than 20 feet. 16.The process of claim 14, wherein at least 25 percent of said totallength of said travel path is located in said initial thermal regulationzone, wherein at least 25 percent of said total length of said travelpath is located in said subsequent thermal regulation zone.
 17. Theprocess of claim 13, wherein the maximum linear distance between any twopoints on said travel path is not more than 200 feet and wherein saidentire liquid contact zone can fit within a cuboid having a volume ofnot more than 100,000 cubic feet.
 18. The process of claim 13, theaverage residence time of said articles in said RF heating zone is notmore than 10 percent of the average residence time of said articles insaid liquid contact zone, wherein the average residence time of saidarticles in said liquid contact zone is in the range of 20 to 240minutes.
 19. The process of claim 13, wherein the average differencebetween the maximum and minimum temperatures within each of saidarticles exiting said RF heating zone is not more than 20° C., whereinthe average difference between the temperatures at the geometric centersof adjacent articles exiting said RF heating zone is not more than 2°C., wherein the average temperature at the geometric center of saidarticles exiting said RF heating zone is at least 90° C., wherein thelength of said article travel path through said RF heating zone is notmore than 10 feet.
 20. The process of claim 13, wherein said subsequentthermal regulation zone includes a hold zone and at least one coolingzone downline of said hold zone, wherein the average temperature at thegeometric center of said articles in said hold zone is maintained at orabove the average temperature at the geometric center of said articlesexiting said RF heating zone, wherein the average residence time of saidarticles in said RF heating zone is 5 to 50 percent of the averageresidence time of said articles in said hold zone.
 21. The process ofclaim 13, wherein said articles have a dielectric constant in the rangeof 20 to 150 and a dielectric loss factor in the range of 10 to 1500,wherein said articles have a volume of at least 8 cubic inches.
 22. Theprocess of claim 13, wherein said articles are submerged in said liquidduring at least a portion of said heating in said RF heating zone,wherein said heating includes transmitting RF energy toward said RFheating zone through a liquid-filled waveguide located outside of saidRF heating zone, wherein said liquid-filled waveguide is filled with thesame liquid as said liquid within which said articles in said RF heatingzone are submerged.
 23. The process of claim 13, wherein said conveyline comprises at least one helical conveyor in said initial thermalregulation zone and at least one helical conveyor in said subsequentthermal regulation zone.
 24. A system for sterilizing or pasteurizingarticles using radio frequency (RF) energy, said system comprising: (a)an initial thermal regulation zone for promoting temperature uniformityof said articles; (b) an RF heating zone for heating said articles withRF energy; (c) a subsequent thermal regulation zone for cooling saidarticles; and (d) at least one convey line for transporting saidarticles along a non-linear article travel path through said initialthermal regulation, RF heating, and subsequent thermal regulation zones,wherein said initial thermal regulation zone comprises an inlet forreceiving said articles and said final thermal regulation zone comprisesan outlet for discharging said articles, wherein said convey line isconfigured such that the total length of said article travel path fromsaid inlet to said outlet is at least 10 times greater than the lineardistance between said inlet and said outlet.
 25. The system of claim 24,wherein the total length of said article travel path is at least 1,000feet, wherein the length of said article travel path through said RFheating zone is not more than 20 feet.
 26. The system of claim 24,wherein at least 25 percent of the total length of said article travelpath is located in said initial thermal regulation zone, wherein atleast 25 percent of the total length of said article travel path islocated in said subsequent thermal regulation zone.
 27. The system ofclaim 24, wherein the maximum linear distance between any two points onsaid article travel path is not more than 200 feet, wherein said entireliquid contact zone can fit within a cuboid having a volume of not morethan 100,000 cubic feet.
 28. The system of claim 24, wherein said conveyline comprises at least one helical conveyor in said initial thermalregulation zone and at least one helical conveyor in said subsequentthermal regulation zone.
 29. The process of claim 24, wherein saidsubsequent thermal regulation zone includes a high-temperature holdzone, a high-pressure cooling zone, a pressure lock, and a low-pressurecooling zone.